
Class. 
Book 



J^^ f2rra^^ 



7^k 



ELEMENTS 



AGRICULTURAL CHEMISTRY, 



A COURSE OF LECTURES 



THE BOARD OF AGRICULTURE. 






BY SIR HUMPHRY DAVY, LL. D. 
F. B. S. L. & E. ivi. R. I. 

Member of the Board of Agriculture, ofjthe Ho3ral Irish Acaalemy, of the 

Academies of St. Petersburgh, Stockholm, Berlin, Philadelphia, &c. 

and Honorary Professor oi Chemistry to the Royal Institution. 



PHILADELPHIA : 

Published by John Conrad & Co. Philadelphia : Fielding Lucas, jr, 

Baltimore ; Robert Gray, Alexandria : and William F. Gray, 

Fredericksburg, (Vir) 

1815. 















\ 



%^^ 



TO THE 

PRESIDENT AND MEIMBEKS 

OF 

THE BOARD OF AGRICULTURE 

FOR THE YEAR 1812. 

THESE LECTURES, 

PUBLISHED AT THEIR REQUEST, 

ARE INSCRIBED, 
AS A TESTIMONY OF THE RESPECT OF THE AUTHOR, 



HIS GRATITUDE FOR THE ATTENTION WITH WHICH 
THEY HAVE BEEN RECEIVED. 



ADVERTISEMENT. 



DURING ten years, since 1802, 1 have had the 
honour, every Session, of delivering Courses of Lec- 
tures before the Board of Agriculture. I have endea- 
voured, at all times, to follow in them the progress of 
chemical discovery j they have therefore varied every 
year : and such is the rapidity with which Chemistry 
is extending, that some alterations and improvements 
were rendered necessary at the time they were prepar- 
ing for the press. 

The Duke of Bedford has enabled me to stamp a 
value upon this work, by permitting me to add to it the 
results of the experiments instituted by His Grace 
upon the quantity of produce afforded by the different 
grasses. 

I am indebted for much useful information to 
many members of the Board ; of which acknowledg- 
ments will be found in the body of the work. If there 
are any omisssions on this head, I trust they will be 
attributed to defect of recollection, and not to any 
want of candour or of gratitude. 

Where I have derived any specific statements from 
books, I have always quoted the authors ; but I have 



VI ADVERTISEMENT. 

not always made references to such doctrines as are 
become current, the authors of which are well known ; 
and which may be almost considered as the property 
of all enlightened minds. 

Amongst books to which I have not referred for 
any particular facts, but which contain much useful 
general information, I shall mention the Earl of Dun- 
donald's Treatise on the connection of Chemistry with 
Agriculture ; Mr. Rennie's Dissertations on Peat ; and 
the General Report of the Agriculture of Scotland. 
This last work did not come into my hands till the 
concluding sheets of these Lectures were printing. 
Had it been in circulation before, I should have profit- 
ed by many statements given in it, particularly those 
of the opinions of the enlightened Professor of Agri-. 
culture in the University of Edinburgh; and I should 
have dwelt with satisfaction on the importance given 
to some chemical doctrines by his experience. 



Berkeley Square, 
March^ 21 1813. 



CONTENTS. . 



LECTURE I. page. 

Introduction. General Views of the Objects of the course, 
and of the order in which they are to be discussed 3 

LECTURE n. 
Of the general Powers of iMatter which influence Vegeta- 
tion ; of Gravitation, of Cohesion, of Chemical Attrac- 
tibn, of Heat, of Light, of Electricity, ponderable Sub- 
stances, Elements of Matter, particularly those found in 
Vegetables, Laws of their Combinations and Arrange- 
ments .---.-.„.3S 

LECTURE IIL 

On the Organization of Plants. Of the Roots, Trunk, and 
Branches ; of their Structure. Of the Epidermis. Of 
the cortical, and alburnous Parts of Leaves, Flowers, and 
Seeds, Of the Chemical Constitution of the Organs of 
Plants, and the Substances found in them. Of mucila- 
ginous, saccharine, extractive, resinous, and oily Sub- 
stances, and other vegetable Compounds, their Ar- 
rangements in the organs of Plants, their Composition, 
Changes, and Uses - ---.,. 50 

LECTURE IV. 
On Soils : their constituent Parts. On the Analysis of 
Soils. Of the Uses of the Soil. Of the Rocks and 
Strata found beneath Soils. Of the Improvement of 
Soils. 135 

. LECTURE V. 

On the Nature and Constitution of the Atmosphere, and 
its influence on Vegetables* Of the Germination of 



vm CONTENTS. 

Seeds. Of the Functions of Plants in their different 
Stagss of Growth ; with a general view of the progress 
of Vegetation - - -- - - -183 

LECTURE VI. 
Of Manures of vegetable and animal Origin. Of the man- 
ner in which they become the Nourishment of the Plant. 
Of Fermentation and Putrefaction. Of the diffei'ent 
Species of Manures of vegetable Origin ; of the differ- 
ent Species of animal Origin. Of mixed manures. 
General Principles with respect to the use and applica- 
tion of such Manures 239 

LECTURE VII. 
On Manures of mineral Origin, or fossile Manures ; their 
Preparation, and the Manner in which they act. Of 
Lime i.i its different States ; Operation of Lime as a 
]VIanure and a cement ; different combinations of Lime. 
Of Gypsum ; Ideas respecting its use. Of other Neu- 
tro-saline Compounds, employed as Manures. Of Al- 
kalies and alkaline Salts ; of common Salt - - 276 

LECTURE VIII. 
On the improvement of Lands by Burning ; chemical 
Principles of this Operation. On Irrigation and its ef- 
fects. On Fallowing ; its disadvantages and uses. On 
the convertible Husbandry founded on regular rotations 
of different Crops. On Pasture- On various Agricul- 
tural Objects connected with Chemistry. Conclusion 307 

APPENDIX. 

An account of the Results of Experiments on the Produce 
and Nutritive Qualities of different Grasses, and other 
Plants, used as the Food of Animals. 



A 



COUESE OF LECTURES 



QN 



THE ELEMENTS 



OF 



JiGRICULTURdL CHEMISTRT. 



ABNMffia^HKaiaiMUBl 



A 



eOURSE OF LECTURES, &c. 



LECTURE I. 

Jniroductwn. General Views of the Objects of the Course^ 
and of the order in which they are to be disc-ussed. 

It is with great pleasure that I receive the permis- 
sion to address so distinguished and enlightened an 
Audience on the subject of Agricultural Chemistry. 

That any thing which! am able to bring forward, 
should be thought worthy the attention of the Board 
of Agriculture, I consider as an honour; and I shall 
endeavour to prove my gratitude, by employing every 
exertion to illustrate this department of knowledge, 
and to point out its uses. 

In attempting these objects, the peculiar state of 
the enquiry presents many difficulties to a Lecturer. 
Agricultural Chemistry has not yet received a regular 
and systematic form. It has been pursued by compe- 
tent experimenters for a short time only; the doctrines 
have not as yet been collected into any elementary trea- 
tise; and on an occasion when I am obliged to trust 
so much to iny own arrangem.ents, and to my own 



C 4 3 

limited information, I cannot hut feel diffident as to 
the interest that may be excited, and doubtful of the 
success of the undertaking. I know, however, that 
your candour will induce you not to expect any thing 
like a finished work upon a science as yet in its infancy; 
and I am sure you will receive with indulgence the 
first attempt made to illustrate it, io a distinct course 
of public lectures. 

Agricultural Chemistry has for its objects all 
those changes in the arrangements of matter connect- 
ed with the growth and nourishment of plants ; the 
comparative values of their produce as food; the con- 
stitution of soils; the manner in which lands are en- 
riched by manure, or rendered fertile by the different 
processes of cultivation. Enquiries of such a nature 
cannot but be interesting and important, both to the 
theoretical agriculturist, and to the practical farmer. 
To the first, they are necessary in supplying most of 
the fundamental principles on which the theory of the 
art depends. To the second, they are useful in afford- 
ing simple and easy experiments for directing his la- 
bours, and for enabling him to pursue a certain and 
systematic plan of improvement. 

It is scarcely possible to enter upon any investiga- 
tion in agriculture without finding it connected, more 
or less, with doctrines or elucidations derived fronji 
chemistry. 

If land be unproductive, and a system of ameliorat- 
ing it is to be attempted, the sure method of obtaining 
the object is by determining the cause of its sterility, 
which must necessarily depend upon some defect in 



C 5 J 

the constitution of the soil, which may be easily dis- 
covered by chemical analysis. 

Some lands of good apparent texture are yet 
sterile in a high degree ; and common observation and 
common practice afford no means of ascertaining the 
cause, or of removing the effect. The application of 
chemical tests in such cases is obvious ; for the soil 
must contain some noxious principle which may be 
easily discovered, and probably easily destroyed. 

Are any of the salts of iron present? rhey maybe 
decomposed by lime. Is there an excess of siliceous 
sand ? the system of improvement must depend on 
the application of clay and calcareous matter. Is 
there a defect of calcareous mattet ? the remedy is 
obvious. Is an excess of vegetable matter indicated ? 
it may be removed by liming, paring, and burning. 
Is there a deficiency of vegetable matter ? it is to be 
supplied by manure. 

A question concerning the different kinds of lime-' 
stone to be employed in cultivation often occurs. To 
determine this fully in the common way of experience, 
would demand a considerable time, perhaps some 
years, and trials which might be injurious to crops; 
but by simple chemical tests the nature of a limestone 
is discovered in a few minutes ; and the fitness of its 
application, whether as a manure for different soils, or 
as a cement, determined. 

Peat earth of a certain consistence and composi- 
tion is an excellent manure ; but there are some varie- 
ties of peats which contain so large a quantity of fer- 
ruginous matter as tj> be absolutely poisonous to plants. 



C 6 J 



Nothing can be more simple than the chemical opera- 
tion for determining the nature, and the probable uses 
of a substance of this kind. 

There has been no question on which more dif- 
ference of opinion has existed, than that of the state 
in which manure ought to be ploughed into the land ; 
whether recent, or when it has gone through the pro- 
cess of fermentation ? and this question is still a sub- 
ject of discussion ; but whoever will refer to the sim- 
plest principles of chemistry, cannot entertain a doubt 
on the subject. As soon as dung begins to decom- 
pose, it throws off its volatile parts, which are the 
most valuable and most efficient. Dung which has fer- 
mented, so as to become a mere soft cohesive mass, 
has generally lost from one third to one half of its 
most useful constituent elements. It evidently should 
be applied as soon as fermentation begins, that it may 
exert its full action upon the plant, and lose none of 
its nutritive powers. 

It would be easv to adduce a multitude of other 
instances of the same kind ; but sufficient I trust has 
been said Xo prove, that the connexion of Chemistry 
with Agriculture is not founded on mere vague specu« 
lation, but that it offers principles which ought to be 
understood and followed, and which in their progres- 
sion and ultimate results, can hardly fail to be highly 
beneficial to the community. 

A view of the objects in this Course of Lectures, 
and of the manner in which they are to be treated, 
will nor, I hope, be considered as an improper intro- 
duction. It will inform you what you are to expect ; 



C 7 J 

it will afford a general idea of the connexion of the 
different parts of the subject, and of their relative im- 
portance ; it will enable me to give some historical 
details of the progress of this branch of knowledge^ 
and to reason from what has been ascertained, con- 
cerning what remains to be investigated and disco- 
vered. 

The phenomena of vegetation must be consider- 
ed as an important branch of the science of organized 
nature ; but though exalted above inorganic matter, 
vegetables are yet in a great measure dependent for 
their existence upon its laws. They receive their nour- 
ishment from the external elements ; they assimilate 
it by means of peculiar organs ; and it is by examin- 
ing their physical and chemical constitution, and the 
substances and powers which act upon them, and the 
modifications which they undergo, that the scientific 
principles of Agricultural Chemistry are obtained. 

According to these ideas, it is evident that the 
study ought to be commenced by some general en- 
quiries into the composition and nature of material 
bodies, and the laws of their changes. The surface 
of the earth, the atmosphere, and the water deposited 
from it, must either together or separately afford all the 
principles concerned in vegetation ; and it is only by 
examining the chemical nature of these principles, 
that we are capable of discovering what is the food of 
plants, and the manner in which this fopd is supplied 
and prepared for their nourishment. The principles 
of the constitution of bodies, consequently, will form 
the first subject for our coixsideration. 



C 8 3 

By methods of analysis dependent upon chemi- 
cal and electrical instruments discovered in late times, 
it has been ascertained that all the varieties of material 
substances may be resolved into a comparatively small 
number of bodies, which, as they are not capable of 
being decompounded, are considered in the present 
state of chemical knowledge as elements. The bodies 
incapable of decomposition at present known are forty- 
seven. Of these, thirty-eight are metals ; seven are 
inflammable bodies ; and two are gasses which unite 
with metals and inflammable bodies, and form with 
them acids, alkahes, earths, or other analogous com- 
pounds. The chemical elements acted upon by at- 
tractive powers combine in different aggregates In 
their simpler combinations, they produce various crys- 
talline substances, distinguished by the regularity of 
their forms. In more complicated arrangements, they 
constitute the varieties of vegetable and animal sub-- 
stances, bear the higher character of organization, 
and are rendered subservient to the purposes of life. 
And by the influence of heat, light, and electrical 
powers, there is a constant series of changes ; matter 
assumes new forms, the destruction of one order of 
beings tends to the conservation of another, solution 
and consolidation, decay and renovation, are connect- 
ed, and whilst the parts of the system continue in 
a state of fluctuation and change, the order and har- 
mony of the whole remain unalterable. 

After a general view has been taken of the na- 
ture of the elements, and of the principles of chemi- 
cal changes, the next object will be the structure and 



C 9 ] 

constitution of plants. In all plants there exists a 
system of tubes or vessels, which in one extremity 
terminate in the roots, and at the other in leaves. It 
is by the capillary action of the roots that fluid mat- 
ter is taken up from the soil. The sap in passing up- 
wards becomes denser, and more fitted to deposit 
sohd matter ; it is modified by exposure to heat, light, 
and air in the leaves ; descends through the bark, 
in its progress produces new organized matter ; and 
is thus in its vernal and autumnal flow, the cause of 
the fermentation of new parts, and of the more per- 
fect evolution of parts already formed. 

In this part of the enquiry I shall endeavour to 
connect together into a general view, the observations 
of the most enlighted philosophers who have studied 
the physiology of vegetation. Those of Grew, Mal- 
pighi, Sennebier, Darwin, and, above all, of Mr. 
Knight. He is the latest enquirer into these interest- 
ing subjects, and his labours have tended most to il- 
lustrate this part of the economy of nature. 

The chemical composition of plants has within 
the last ten years, been elucidated by the experiments 
of a number of chemical philosophers, both in this, 
and in other countries ; and it forms a beautiful part of 
general chemistry j it is too extensive to be treated of 
minutely ; but it will be necessary to dwell upon 
such parts of it, as aflbrd practical inferences. 

If the organs of plants be submitted to chemical 
analysis, it is found that their almost infinite diversity 
of form, depends upon different Sk'angements and 
combinations of a very few of the elements 5 seldo.m 



C 10 ] 

more than seven or eight belong to them, and three con- 
stitute the greatest part of their organized matter ; and 
according to the manner in which these elements are 
disposed, arise the different properties of the products 
of vegetation, whether employed as food, or for other 
purposes and wants of life. 

The value and uses of every species of agricul- 
tural produce, are most correctly estimated ana applied 
when practical knowledge is assisted by principles de- 
rived from chemistry. The compounds in vegetables 
really nutritive as the food of animals, are very few ; 
farina or the pure matter of starch, gluten, vegetable 
jelly, and extract. Of these the most nutritive is 
gluten, which approaches nearest in its nature to ani- 
mal matter, and which is the substance that gives to 
wheat its superiority over other grain. The next in 
order as to nourishing power, is sugar, then farina ; 
and last of all gelatinous and extractive matters. Sim- 
ple tests of the relative nourishing powers of the diifer- 
ent species of food, are the relative quantities of these 
substances that they afford by analysis ; and though 
taste and appearance must influence the consumption 
of all articles in years of plenty, yet they are less at- 
tended to in times of scarcity, and on such occasions 
this kind of knowledge may be of the greatest impor- 
tance. Sugar and farina or starch, are very similar 
in composition, and are capable of being converted 
into each other by simple chemical processes. In the 
discussion of their relations, I shall detail to you the 
results of some recent experiments which will be 
found possessed of applications both to the oeconomy 



C 11 ] 

©f vegetation, and to some important processes of 
manufacture. 

All the varieties of substances found in plants, 
are produced from the sap, and the sap of plants is 
derived from water, or from the fluids in the soil, and 
it is altered by, or combined with principles derived 
from the atmosphere. The influence of the soil, of 
water, and of air, will therefore be the next subject of 
consideration. Soils in all cases consist of a mixture 
of different finely divided earthy matters ; with ani- 
mal or vegetable substances in a state of decomposi- 
tion, and certain saline ingredients. The earthy mat- 
ters are the true basis of the soil ; the other parts, 
whether natural, or artificially introduced, operate in 
the same manner as manures. Four earths generally 
abound in soils, the alumin®us, the siliceous, the cal- 
careous, and the magnesian. These earths, as I have 
discovered, consist of highly inflammable metals 
united to pure air or oxygene ; and they are not, as 
far as we know, decomposed or altered in vegetation. 
The great use of the soil is to afford support to the 
plant, to enable it to fix its roots, and to derive nour- 
ishment by its tubes slowly and gradually, from the so- 
luble and dissolved substances mixed with the earths. 

That a particular mixture of the earths is con- 
nected with fertility, cannot be doubted : and almost 
all sterile soils are capable of being improved, by a 
modification of their earthy constituent parts. I shall 
describe the simplest method as yet discovered of 
analysing soils, and of ascertaining the constitution 
and chemical ingredients which appear to be connect- 



C 12 "J 

ed with fertility and on this subject many of the for- 
mer difficulties of investigation will be found to be re- 
moved by recent enquiries. 

The necessity of water to vegetation, and the lux- 
uriancy of the growth of plants connected with the pre- 
sence of moisture in the southern countries of the old 
continent, led to the opinion so prevalent in the early 
schools of philosophy, that water was the great pro- 
ductive element, the substance from which all things 
were capable of being composed, and into which 
they were finally resolved. The " »«'<"«" /"" ^^-^e'* of 
the poet, " water is the noblest," seems to have 
been an expression of this opinion, adopted by the 
Greeks from the Egyptians, taught by Thales, and 
revived by the alchemists in late times. Van Hel- 
. mont in 1610, conceived that he had proved by a de- 
cisive experiment, that all the products of vegetables 
were capable of being generated from water.- His 
results were shewn to be fallacious by Woodward in 
1691 ; but the true use of waiter in vegetation was 
unknown till 1785; when Mr. Cavendish made the 
grand discoveiy, that it was composed of two elastic 
fluids or gases, inflammable gas or hydrogene, and 
vital gas or oxygene. 

Air, like water, was regarded as a pure element 
by most of the ancient philosophers : a few of the 
chemical enquirers in the sixteenth and seventeeth 
centuries, formed some happy conjectures respecting 
its real nature. Sir Kenelm Digby in 1 660, supposed 
that it contained some saline matter, which was an 
essential food of plants. Boyle, Hooke, and Mayow, 



[ 13 3 

between 1665 and 1680, stated that a small part of it 
only was consumed in the respiration of animals, and 
in the combustion of inflammable bodies ; but the 
true statical analysis of the atmosphere is comparative- 
ly a recent labour, achieved towards the end of the 
last century by Scheele, Priestley, and Lavoisier. 
These celebrated men shewed that its principal 
elements are,Ja^'o gases, oxygene and azote, of which 
the first is essential to flame, and to the life of animals, 
and' that it likewise contains small quantities of 
aqueous vapour, and of carbonic acid gas ; and La- 
voisier proved that this last body is itself a compound 
elastic fluid, consisting of charcoal dissolved in oxy- 
gene. 

Jethro Tull, in his treatise on Horse-hoeing, pub- 
lished in 1733, advanced the opinion that minute 
earthy particles supplied the whole nourishment of the 
vegetable werld ; that air and water were chiefly useful 
in producing these particles from the land ; and that 
manures acted in no other way than in ameliorating the 
texture of the soil, in short, that their agency was 
mechanical. This ingenious author of the new system 
of agriculture having observed the excellent effects 
produced in farming by a minute division of the soil, 
and the pulverisation of it by exposure to dew and air, 
was misled by carrying his principles too far. Duh- 
amel, in a work printed in 1 754, adopted the opinion 
of Tull, and stated that by finely dividing the soil, any 
number of crops might be raised in succession from 
the same land. He attempted also to prove, by di- 
rect experiments, that vegetables of every kind were 



C 1* 1 

capable of being raised without manure. This cele- 
brated horticulturist lived, however, sufficiently long 
to alter his opinion. The results of his later and 
most refined observations led him to the conclusion, 
that no single material afforded the food of plants. 
The general experience of farmers had long before 
convinced the unprejudiced of the truth of the same 
opinion, and that manures were absolutely consumed 
in the process of vegetation. The exhaustion of soils 
by carrying off corn crops from them, and the effects 
of feeding cattle on lands, and of preserving their 
manure, offer familiar illustrations of the principle ; 
and several philosophical enquirers, particularly Has- 
senfratz and Saussure, have shewn by satisfactory ex- 
periments, that animal and vegetable matters deposit- 
ed in soils are absorbed by plants, and become a part 
of their organized matter. But though neither water, 
nor air, nor earth, suppHes the whole of the food of 
plants, yet they all operate in the process of vegeta- 
tion. The soil is the laboratory in which the food is 
prepared. No manure can be taken up by the roots 
of plants unless water is present ; and water or its 
elements exist in all the products of vegetation. The 
germination of seeds does not take place without the 
presence of air or oxygene gas j and in the sunshine 
vegetables decompose the carbonic acid gas of the at- 
mosphere, the carbon of which is absorbed, and be- 
comes a part of their organized matter, and the oxy- 
gene gas, the other constituent, is given off"; and in 
consequence of a variety of agencies, the oeconomy of 
vegetation is made subservient to the general order of 
the system of nature. 



[ 15 ] 

It Is shewn by various researches, that the constitu- 
tion of the atmosphere has been always the same since 
the time that it was first accurately analysed ; and 
this must in a great measure depend upon the powers 
of plants to absorb or decompose the putrifying or de- 
caying remains of animals and vegetables, and the 
gaseous effluvia which they are constantly emitting. 
Carbonic acid gas is formed in a variety of processes 
of fermentation and combustion, and in the respiration 
of animals, and as yet no other process is known in 
nature by which it can be consumed, except vegeta- 
tion. Animals produce a substance which appears to 
be a necessary food of vegetables j vegetables evolve 
a principle necessary to the existence of animals ; and 
these different classes of beings seem to be thus con- 
nected together in the exercise of their living functions 
and to a certain extent made to depend upon each 
other for their existence. Water is raised from the 
ocean, diffused through the air, and poured down 
upon the soil, so as to be applied to the purposes 
of life. The different parts of the atmosphere are 
mingled together by winds or changes of tempera- 
ture, and successively brought in contact with the 
surface of the earth, so as to exert their fertilizing in- 
fluence. The modifications of the soil, and the ap- 
plication of manures are placed within the power of 
man, as if for the purpose of awakening his industry 
and of calling forth his powers. 

The theory of the general operation of the more 
compound manures may be rendered very obvious by 
simple chemical principles 5 but there is still much 



[16 J 

to be discovered with regard to the best methods 
of rendering animal and vegetable substances soluble ; 
with respect to the processes of decomposition, how 
they may be accelerated or retarded, and the means 
of producing the greatest effects from the materials 
employed : these subjects will be attended to in the 
Lecture on Manures. 

Plants are found by analysis to consist princi- 
pally of charcoal and aeriform matter. They give 
out by distillation volatile compounds, the elements 
of which are pure air, inflammable air, coally matter, 
and azote, or that elastic substance which forms a 
great part of the atmosphere, and which is incapable 
of supporting combustion. These elements they gain 
either by their leaves from the air, or by their roots 
from the soil. All manures from organized substan- 
ces contain the principles of vegetable matter, which 
during putrefaction are rendered either soluble in 
water or aeriform — and in these states they are capa- 
ble of being assimilated to the vegetable organs. No 
one principle affords the pabulum of vegetable hfe ; 
it is neither charcoal nor hydrogene, nor azote nor 
oxygene alone ; but all of them together in various 
states and various combinations. Organic substances 
as soon as they are deprived of vitality, begin to pass 
through a series of changes which end in their com- 
plete destruction, in the entire separation and dissipa- 
tion of the parts. Animal matters are the soonest des- 
troyed by the operation of air, heat, and light. Vege- 
ble substances yield more slowly, but finally obey the 
same laws. The periods of the application of manures 



[ 17 ] 

from decomposing animal and vegetable substances 
depend upon the knowledge of these principles, and 
I shall be able to produce some new and important 
facts founded upon them, which I trust will remove 
all doubt from this part of agricultural theory. 

The chemistry of the more simple manures ; the 
manures which act in very small quantities, such as 
gypsum, alkalies, and various saline substances, has 
hitherto been exceedingly obscure. It has been gen- 
erally supposed that these materials act in the vegetable 
CEconomy in the same manner as condiments or stimu- 
lants in the animal oeconomy, and that they render the 
common food more nutritive.- It seems, however, a 
much more probable idea, that they are actually a 
part of the true food of plants, and that they supply 
that kind of matter to the vegetable fibre, which is 
analogous to the bony matter in animal structures. 

The operation of gypsum, it is well known, is 
extremely capricious in this country, and no certain 
data have hitherto been offered for its application. 

There is, however, good ground for supposing 
that the subject will be fully elucidated by chemical 
enquiry. Those plants which seem most benefited by 
its application, are plants which always afford it on 
analysis. Clover, and most of the artificial grasses, con- 
tain it, but it exists in very minute quantity only in 
barley, wheat and turnips. Many peat ashes which 
are sold at a considerable price, consist in great part 
of gypsum, with a little iron, and the first seems to 
be their most active ingredient. I have examined 
several of the soils to which these ashes are success- 

D 



[18 ] ■ 

fully applied, and I have found in them no sensible 
quantity of gypsum. In general, cultivated soils contain 
sufficient of this substance for the use of the grasses ; 
in such cases, its application cannot be advantageous. 
For plants require only a certain quantity of manure ; 
an excess may be detrimental, and cannot be useful. 

The theory of the operation of alkaline substan- 
ces, is one of the parts of the chemistry of agriculture, 
most simple and distinct. They are found in all plants 
and therefore may be regarded as amongst their es- 
sential ingredients. From their powers of combina- 
tion likewise, they may be useful in introducing vari- 
ous principles into the sap of vegetables, which may 
be subservient to their nourishment. 

The fixed alkalies which were formerly regarded 
as elementary bodies, it has been my good fortune to 
decompose. They consist of pure air, united to high- 
ly inflammable metallic substances ; but there is no 
reason to suppose that they are reduced into their 
elements in any of the processes of vegetation. 

In this part of the course I shall dwell at consi- 
derable length on the important subject of Lime, and 
I shall be able to ofter some novel views. 

Slacked lime was used by the Romans for man- 
uring the soil in which fruit trees grew. This we are 
informed by Pliny. Marie had been employed by the 
Britons and the Gauls from the earliest times, as a 
top dressing for land. But the precise period in 
which burnt lime first came into general use in the cul- 
tivation of land, is, I believe, unknown. The origin 
of the application from the early practices is sufficient- 



[ 19 J 

ly obvious j a substance which had been used with 
success in gardening, must have been soon tried in 
in farming ; and in countries where marie was not to 
be found, calcined limestone would be naturally em- 
ployed as a substitute. 

The elder writers on agriculture had no correci: 
notions of the nature of lime, limestone and marie, or 
of their "effects ; and. this was the necessary conse- 
quence of the imperfection of the chemistry of the 
age. Calcareous matter was considered by the alche- 
mists as a peculiar earth, which in the fire became 
combined with inflammable acid j and Evelyn and 
Harthb, and still later, Lisle, in their works on hus- 
bandry, ha;ve characterized it merely as a hot manure 
of use in cold lands. It is to Dr. Black of Edinburgh 
that our first distinct rudiments of knowledge on the 
subject are owing. About the year 1755, this cele- 
brated professor proved, by the most decisive experi- 
ments, that limestone and all its modifications, mar- 
bles, chalks, and marles, consist principally of a pecu- 
liar earth united to an aerial acid : that the acid is 
given out in burning, occasioning a loss of more than 
40 per cent., and that the lime in consequence becomes 
caustic. 

These important facts immediately applied with 
equal certainty to the explanation of the uses of lime, 
both as a cement and as a manure. As a cement, 
lime applied in its caustic state acquires its hardness 
and durability, by absorbing the aerial (or as it has 
been since called carbonic) acid, which always exists 
in small quantities in the atmosphere, it becomes as 
it were again limestone. 



C 20 ] 

Chalks, calcareous marles, or powdered lime- 
stones, act merely by forming an us- ful earthy ingre- 
dient of the soil, and their efficacy is proportioned to 
the deficiency of calcareous matter, which in larger 
or smaller quantities seems to be an essential ingre- 
dient of all fertile soils ; necessary perhaps to their 
proper texture, and as an ingredient in the organs of 
plants. 

Burnt lime, in its first effect, acts as a decompo- 
sing agent upon animal or vegetable matter, and seems 
to bring it into a state on which it becomes more 
rapidly a vegetable nourishment ; gradually, however, 
the lime is neutralized by carbonic acid, and conver- 
ted into a substance analogous to chalk ; but in this 
case it more perfectly mixes with the other ingredients 
oi the soil, is more generally diffused and finely di- 
vided ; and it is probably more useful to land than 
any calcareous substance in its natural state. 

The most considerable fact made known with 
regard to limestone within the last few years, is owing 
to Mr. Tennant. It had been long known that a par- 
ticular species of limestone found in different parts of 
the North of England, when applied in its burnt and 
slacked state to land in considerable quantities, occa- 
sioned sterility, or considerably injured the crops for 
many years. Mr. Tennant in ] 800, by a chemical 
examination of this species of limestone, ascertained, 
that it differed from common limestones by containing 
magnesian earth ; and by several experiments he 
proved that this earth was prejudicial to vegetation, 
when applied in large quantities in its caustic state. 



r 21 3 

Under common circumstances the lime from the mag- 
nesian limestone is, however, used in moderate quan- 
tities upon fertile soils in Leicestershire, Derbyshire, 
and Yorkshire, with good effect ; and it may be ap- 
plied in greater quantities to soils containing very large 
proportions of vegetable matter. Magnesia when 
combined with carbonic acid gas, seems not to be pre- 
judicial to vegetation, and in soils rich in manure, it 
is speedily supplied with this principle from the de- 
composition of the manure. 

After the nature and operation of manures have 
been discussed, the next, and the last subject for our 
consideration, will be some of the operations of hus- 
bandry capable of elucidation by chemical principles. 

The chemical theory of fallowing is very simple. 
Fallowing affords no new source of riches to the soil. 
It merely tends to produce an accumulation of decern 
posing matter, which in the common course of crops 
would be employed as it is formed, and it is scarcely 
possible to imagine a single instance of a cultivated 
soil, which can be supposed to remain fallow for a 
year with advantage to the farmer. The only cases 
where this practice is beneficial seems to be in the des- 
truction of weeds, and for cleansing foul soils. 

The chemical theory of paring and burning, I 
§hall discuss fully in this part of the Course. 

It is obvious that in all cases it must destroy a 
certain quantity of vegetable matter, and must be 
principally useful in cases in which there is an excess 
of this matter in soils. Burning, likewise renders 
clays less coherent, and in this way greatlv improves 



C ^^ 1 

their texture, and causes them to be le^s permeable 
to water. 

The instances in which it must be obviously pre- 
judicial, are those of sandy dry siliceous soils, contain- 
ing little animal or vegetable matter. Here it can 
only be destructive, for it decomposes that on which 
the soil depends for its productiveness. 

The advantages of irrigation, though so lately a 
subject of much attention, were well known to the 
ancients ; and more than two centuries ago the prac- 
tice was recommended to the farmers of our country 
by Lord Bacon ; " meadow-watering,*' according to 
the statements of this illustrious personage, (given in 
his Natural History, in the article Vegetation,) acts 
not only by supplying useful moisture to the grass ; 
but likewise the water carries nourishment dissolved 
in it, and defends the roots from the effects of cold. 

No general principles can be laid down respecting 
the comparative merit of the different systems of culti- 
vation, and the different systems of crops adopted in 
different districts, unless the chemical nature of the 
soil, and the physical circumstances to which it is ex- 
posed are fully known. Stiff coherent soils are those 
most benefited by minute division and aeration, and in 
the drill system of husbandry, these effects are pro- 
duced to the greatest extent ; but still the labour and 
expense connected with its application in certain dis- 
tricts, may not be compensated for by the advantages 
produced. Moist cHmates are best fitted for raising 
the artificial grasses, oats, and broad leaved crops j 
stiff aluminous soils, in general, are most adapted for 



C 23 ] 

wheat erops, and calcareous soils produce excellent 
sain-foin and clover. 

Nothing is more wanting in agriculture, than ex- 
periments in which all the circumstances are minutely 
and scientifically detailed. This art will advance with 
rapidity in proportion as it becomes exact in its 
methods. As in physical researches all the causes 
should be considered ; a difference in the results may 
be produced, even by the fall of a half an inch of rain 
more or less in the course of a season, or a few de- 
grees of temperature, or even by a shght difference in 
the sub-soil, or in the inclination of the land. 

Information collected after views of distinct en- 
quiry, would necessarily be more accurate, and more 
capable of being connected with the general principles 
of science ; and a few histories of the results of truly 
philosophical experiments in agricultural chemistry, 
would be of more value in enlightening and benefitting 
the farmer, than the greatest possible accumulation of 
imperfect trials, conducted merely in the empirical 
spirit. It is no unusual occurence for persons who 
argue in favour of practice and experience, to con- 
demn generally all attempts to improve agriculture by 
philosophical enquiries and chemical methods. That 
much vague speculation may be found in the works of 
those who have lightly taken up agricultural chemis- 
try, it is Impossible to deny. It is not uncommon to 
find a number of changes rung upon a string of tech- 
nical terms, such as oxygene, hydrogene, carbon, and 
azote, as if the science depended upon words, rather 
than upon things. But this is in fact an argument for 



r 24 3 

the necessity of the establishment of just principles of 
chemistry on the subject. Whoever reasons upon 
agricukure, is obliged to recur to this science. He 
feels that it is scarcely possible to advance a step with- 
out it ; and if he is satisfied with insufficient views, it 
is not because he prefers them to accurate knowledge, 
but generally because they are more current. If a 
person journeying in the night wishes to avoid being 
led astray by the ignis fatuus, the most secure method 
is to carry a lamp in his own hand. 

It has been said, and undoubtedly with great 
truth, that a philosophical chemist would most proba- 
bly make a very unprofitable business of farming ; and 
this certainly would be the case, if he were a mere 
philosophical chemist ; and unless he had served his 
apprenticeship to the practice of the art, as well as to 
the theory. But there is reason to believe, that he 
w^ould be a more successful agriculturist than a per- 
son equally uninitiated in farming, but ignorant of 
chemistry altogether ; his science, as far as it went, 
would be useful to him. But chemistry is not the 
only kind of knov/ledge required, it forms a small part 
of the philosophical basis of agriculture ; but it is an 
important part, and whenever applied in a proper 
manner must produce advantages. 

In proportion as science advances all the princi- 
ples become less complicated, and consequently more 
useful. And it is then that their application is most 
advantageously made to the arts. The common la- 
bourer can never be enlightened by the general doc- 
trines of philosophy, but he will not refuse to adopt 



C 25 3 

any practice, of the utility of which he is fully con- 
vinced, because it has been founded upon these prin- 
ciples. The manner can trust to the compass, 
though he may be wholly unacquainted with the dis- 
coveries of Gilbert on magnetism, or the refined prin- 
ciples of that science developed by the genius of 
^pinus. The dyer will use his bleaching liquor, 
even though he is perhaps ignorant not only of the 
constitution, but even of the name of the substance 
on which its powers depend. The great purpose of 
chemical investigation in Agriculture, ought undoubt- 
edly to be the discovery of improved methods of cul- 
tivation. But to this end, general scientific principles 
and practical knowledge, are alike necessary. The 
germs of discovery are often found in rational specu- 
lations ; and industry is never so efficacious as when 
assisted by science. 

It is from the higher classes of the community, 
from the proprietors of land ; those who are fitted by 
their education to form enlightened plans, and by their 
fortunes to carry such plans into execution ; it is from 
these that the principles of improvement must flow to 
the labouring classes of the community ; and in all 
cases the benefit is mutual ; for the interest of the 
tenantry must be always likewise the interest of the 
proprietors of the soil. The attention of the labourer 
will be more minute, and he will exert himself more 
for improvement when he is certain he cannot deceive 
his employer, and has a conviction of the extent cf 
his knowledge. Ignorance in the possessor of an 
estate of the manner in which it ought to be treated^ 

E 



[ 26 ] 

often leads either to inattention or injudicious prac* 
tices in the tenant or the bailiff. " Agrum pes- 
simum ?nulctari ciijus Doniinus non docet sed audit vil- 

Ileum.'* 

There is no idea more unfonnded than that a 
great devotion of time, and minute knowledge of gen- 
eral chemistry is necessary for pursuing experiments 
on the nature of soils or the properties of manures. 
Nothing can be more easy than to discover whether a 
soil effervesces, or changes colour by the action of an 
acid, or whether it burns when heated ; or what 
weight it loses by heat : and yet these simple indica- 
tions may be of great importance in a system of culti- 
vation. The expence connected with chemical enqui- 
ries is extremely trifling ; a small closet is sufficient 
for containing all the materials required. The most 
important experiments may be made by means of a 
small portable apparatus ; a few phials, a few acids, a 
lamp and a crucible are all that are necessary, as I shall 
endeavour to prove to you, in the course of these 
lectures. 

It undoubtedly happens in agricultural chemical 
experiments conducted after the most refined theo- 
rectical views, that there are many instances of failure, 
for one of success ; and this is inevitable from the 
capricious and uncertain nature of the causes that 
operate, and from the impossibility of calculating on 
all the circumstances that may interfere ; but this is 
far from proving the inutility of such trials ; one hap- 
py result which can generally improve the methods 
of cultivation is worth the labour of a whole life ; and 



[ 27 ] 

an unsuccessful experiment well observed, must esta- 
blish some truth, or tend to remove some prejudice. 

Even considered merely as a philosophical 
science, this department of knowledge is highly worthy 
of cultivation. For what can be more delightful than 
to trace the forms of living beings and their adapta- 
tions and peculiar purposes ; to examine the progress 
of inorganic matter in its different processes of 
change, till it attain its ultimate and highest destina- 
tion ; its subserviency to the purposes of man. 

Many of the sciences are ardently pursued, and 
considered as proper objects of study for all refined 
minds, merely on account of the intellectual pleasure 
they afford ; merely because they enlarge our views 
of nature, and enable us to thinly more correctly with 
respect to the beings and objects surrounding us. How 
much more then is this department of enquiry worthy 
of attention, in which the pleasure resulting from the 
love of truth and of knowledge is as great as in any 
other branch of philosophy, and in which it is likewise 
connected with much greater practical benefits an4 
advantages. " Nihil est melius, nihil uberius, nihil ho- 
mine libera dignius.** 

Discoveries made In the cultivation of the earth, 
are net merely for the time and country in which they 
are^ developed, but they may be considered as extend- 
ing to future ages, and as ultimately tending to bene- 
fit the whole human race ; as affording subsistence 
for generations yet to come ; as multiplying life, and 
not only multiplying hfe, but likewise providing for 
its enjoyment. 



28 J 



LECTURE II. 

Of the general Powers of Matter which influence Vegeta- 
tion. Of Gravitation^ of Cohesion, of chemical Attrac- 
tion, of Heat, of Light, of Electricity, ponderable 
Substances, Ele?nents of Matter, particularly those 
found in Vegetables, Laws of their Combinations and 
Arrangements, 

THE great operations of the farmer are directed 
towards the production or improvement of certain 
classes of vegetables ; they are either mechanical or 
chemical, and are, consequently, dependant upon' the 
laws which govern common matter. Plants themselves 
are, to a certain extent, submitted to these laws ; and 
it is necessary to study their effects both in consider- 
ing the phaenomena of vegetation, and the cultivation 
of the vegetable kingdom. 

One of the most important properties belonging 
to matter is gravitation, or the power by which mas- 
ses of matter are attracted towards each other. It is 
in consequence of gravitation that bodies thrown into 
the atmosphere fall to the surface of the earth, and that 
the different parts of the globe are preserved in their 
proper positions. Gravity is exerted in proportion to 
the quantity of matter. Hence all bodies placed above 
the surface of the earth fall to it in right lines, which 
if produced would pass through its centre j and a 



[ 29 3 

body falling near a high mountain, is a little bent 
out of the perpendicular direction by the attraction 
of the mountain, as has been shewn by the experi- 
ments of Dr. Maskelyne on Schehallien. 

Gravitation has a very important influence on 
the growth of plants ; and it is rendered probable, by 
the experiments of Mr. Knight, that they owe the pe- 
culiar direction of their roots and branches almost en- 
tirely to this force. 

That gentleman fixed some seeds of the garden 
^ean on the circumference of a wheel, which in one 
instance was placed vertically, and in the other hori- 
zontally, and made to revolve, by means of another 
wheel worked by water, in such a manner, that the 
number of the revolutions could be regulated j the 
beans were supplied with moisture, and were placed 
under circumstances favourable to germination. The 
greatest velocity of motion given to the wheel was 
such, that it performed 250 revolutions in a minute. 
It was found that in all cases the beans grew, and that 
the direction of the roots and stems was influenced by 
the motion of the wheel. When the centrifugal force 
was made^ superior to the force of gravitation, which 
was supposed to be done when the vertical wheel per- 
formed 1 50 revolutions in a minute, all the radicles, 
in whatever way they were protruded from the po- 
sition of the seeds, turned their points outwards from 
the circumference of the wheel, and in their subse- 
quent growth receded nearly at right angles from its 
axis ; the germens, on the contrary, took the opposite 
direction, and in a few days their points all met in 
the centre of the wheel. 



C so ] 

When the centrifugal force was made merely to 
modify the force of gravitation in the horizontal wheel 
when the greatest volocity of revolution was given, 
the radicles pointed downwards about ten degrees be- 
low, and the germens as many degrees above the 
horizontal line of the wheel's motion ; and the devia- 
tion from the perpendicular was less in proportion, 
as the motion was less rapid.* 

These facts afford a rational solution of this cu- 
rious problem, respecting which different philosophers 
have given such different opinions ; some referring it 
to the nature of the sap, as De la Hire, others, as 
Darwin, to the living powers of the plant, and the 
stimulus of air upon the leaves, and of moisture upon 
the roots. The effect is now shewn to be connected 
with mechanical causes ; and there seems no other 
power in nature to which it can with propriety be 
referred but gravity, which acts universally, and 
which must tend to dispose the parts to take a uni- 
form direction. 

If plants In general owe their perpendicular di- 
rection to gravity, it is evident that the number of 
plants upon a given part of the earth's circumference, 
cannot be increased by making the surface irregular, 
as some persons have supposed. Nor can more stalks 
rise on a hill than on a spot equal to its base ; for the 
slight effect of the attraction of the hill, would be only 



• Fig. 1 represents the form of the experiment when the vertical wheel was 
made to perform ISO revolutions in a minute. 

Fig. 2 cepresents the case in which the horizental wheel performed 250 I'ero- 
lotions. 



C SI ] 

to make the plats deviate a very little from the per- 
pendicular. Where horizontal layers are pushed 
forth, as in certain grasses, particularly such as the 
fiorin, lately brought into notice by Dr. Richardson, 
more food may, however, be produced upon an irre- 
gular surface ; but the principle seems to apply strict- 
ly to corn crops. 

The direction of the radicles and germens is such 
that both are supplied with food, and acted upon by 
those external agents which are necessary for their 
developement and growth. The roots come in con- 
tact with the fluids in the ground ; the leaves are ex- 
posed to light and air ; and the same grand law which 
preserves the planets in their orbits, is thus essential 
to the functions of vegetable life. 

When two pieces of polished glass are pressed 
together they adhere to each other, and it requires 
some force to separate them. This is said to depend 
upon the attraction of cohesion. The same attraction 
gives the globular form to drops of water, and enables 
fluids to rise in capillary tubes ; and hence it is some- 
times called capillary attraction. This attraction, like 
gravitation, seems common to all matter, and may be 
a modification of the same general force ; like gravi- 
tation, it is of great importance in vegetation. It pre- 
serves the forms qf aggregation of the parts of plants, 
and it seems to be a principal cause of the absorption 
of fluids by their roots. 

If some pure magnesia, the calcined magnesia o£ 
druggists, be thrown into distilled vinegar, it gradu- 
ally disolves. This is said to be owing to chemical 



C 32 ] 

attraction, the power by which different species of 
matter tend to unite into one compound. Various 
kinds of matter unite with different degrees of force : 
thus sulphuric acid and magnesia unite with more 
readiness than distilled vinegar and magnesia ; and if 
sulphuric acid be poured into a mixture of vinegar 
and magnesia, in which the acid properties of the 
vinegar have been destroyed by the magnesia, the vine- 
gar will be set free, and the sulphuric acid will take 
its place. This chemical attraction is likewise called 
chemical affinity. It is active in most of the phseno- 
mena of vegetation. The sap consists of a number of 
ingredients, dissolved in water by chemical attraction ; 
and it appears to be in consequence of the operation 
of this power, that certain principles derived from the 
sap are united to the vegetable organs. By the laws 
of chemical attraction, different products of vegetation 
are changed, and assume new forms : the food of 
plants is prepared in the soil ; vegetable and animal 
remains are changed by the action of air and water, 
and made fluid or aeriform ; rocks are broken down 
and converted into soils ; and soils are more finely 
divided and fitted as receptacles for the roots of 
plants. 

The different powers of attraction tend to pre- 
serve the arrangements of matter, or to unite them in 
new forms. If there were no opposing powers, there 
would soon be a state of perfect quiescence in nature, 
a kind of eternal sleep in the physical world. Gravi- 
tation is continually counteracted by mechanical 
agencies, by projectile motion, or the centrifugal 



I 33 2 

force ; and their joint agencies occasion the morion of 
the heavenly bodies. Cohesion and chemical attrac- 
tion are opposed by the repulsive energy of beat, and 
the harmonious cycle of terrestrial changes is pro- 
-duced by their mutual operations. 

Heat is capable of being communicated from one 
body to other bodies ; and its common effect is to 
expand them, to enlarge them in all their dimensions. 
This is easily exemplified. A solid cylinder of metal 
after being heated will not pass through a ring barely 
sufficient to receive it when cold. When water is 
heated in a globe of glass having a long slender neck, 
it rises in the neck ; and if heat be applied to air con- 
fined in such a vessel inverted above water, it makes 
its escape from the vessel and passes through the wa- 
ter. Thermometers are instruments for measuring 
degrees of heat by the expansion of fluids in narrow 
tubes. Mercury is generally used, of which 100,000 
parts at the freezing point of water become 101,83.5 
parts at the boiling point, and on Fahrenheit's scale 
these parts are divided into 180 degrees. Solids, by 
a certain increase of heat, become fluids, and fluids 
gasses, or elastic fluids. Thus ice is converted by heat 
into water, and by still more heat it becomes steam : 
and heat disappears, or, as it is called, is rendered 
latent during the conversion of solids into fluids, or 
fluids into gasses, and reappears or becomes sensible 
when gasses become fluids, or fluids solids : hence 
cold is produced during evaporation, and heat during 
the condensation of steam. 



C ..34 ] 

There are a few exceptions to the law of expansion 
of bodies by heat, which seem to depend either upon 
some change in their chemical constitution, or on their 
becoming crystallized. Clay contracts by heat, 
which seems to be owing to its giving off water. Cast 
iron and antimony, when melted, crystallize in cool- 
ing and expand. Ice is much lighter than water. 
Water expands a little even before it freezes, and it is 
of the greatest density at about 41° or 42", the freez- 
ing point being S2° ; and this circumstance is of con- 
siderable importance in the general oeconomy of na- 
ture. The influence of the changes of seasons and 
of the position of the sun on the phaenomena ©f vege- 
tation, demonstrates the effects of heat on the func- 
tions of plants. The matter absorbed from the soil 
must be in a fluid state to pass into their roots, and 
when the surface is frozen they can derive no nour- 
ishment from it. The activity of chemical changes 
likewise is increased by a certain increase of tempera- 
ture, and even the rapidity of the ascent of fluids by 
capillary attraction. 

This last fact is easily shewn by placing in each 
of two wine glasses a similar hollow stalk of grass,- so 
bent as to discharge any fluid in the glasses slowly by 
capillary attraction ; if hot water be in one glass, and 
cold water in the other, the hot water will be dis- 
charged much more rapidly than the cold water. The 
fermentation and decomposition of animal and vegeta- 
ble substances require a certain degree of heat, which 
is consequently necessary for the preparation of the 
food of plants j and as evaporation is more rapid in 



C 35 3 

proportion as the temperature is higher, the superflu- 
ous parts of the sap are most readily carried ofF at the 
time its ascent is quickest. 

Two opinions are current respecting the nature 
of heat*, By some philosophers it is conceived to be 
a peculiar subtile fluid, of which the particles repel 
each other, but have a strong attraction for the parti- 
cles of other matter. By others it is considered as 
a motion or vibration of the particles of matter, 
which is supposed to differ in velocity in different 
cases, and thus to produce the different degrees of 
temperature. Whatever decision be ultimately made 
respecting these opinions, it is certain that there h 
matter moving in the space between us and the hea- 
venly bodies capable of communicating heat j the mo- 
tions of which are rectilineal : thus the solar rays 
produce heat in acting on the surface of the earth. 
The beautiful experiments of Dr. Herschel have 
shewn that there are rays transmitted from the sun 
which do not illuminate ; and which yet produce 
more heat than the visible rays ; and Mr. Ritter and 
Dr. Wollaston have shewn that there are otber invisi- 
ble- rays distinguished by their chemical effects. 

The different influence of the different solar rays 
on vegetation have not yet been studied j but it is cer- 
tain that the rays exercise an influence independent of 
the heat they produce. Thus plants kept in the dark 
in a hot-house grow luxuriantly, but they never gaint 
their natural colours ; their leaves are white or pale, 
and their juices watery and peculiarly saccharince 



[ 36 J 

When a piece of sealing-wax is rubbed by <£ 
woollen cloth, it gains the power of attracting light 
bodies, such as feathers or ashes. In this state it is 
said to be electrical ; and if a metallic cylinder, placed 
upon a rod of glass, is brought in contact with the 
sealing-wax, it likewise gains the momentary power of 
attracting light bodies, so that electricity like heat is 
communicable. When two light bodies receive the 
same electrical influence, or are electrified by the 
same body, they repel each other. When one of them 
is acted on by sealing-wax, and the other by glass that 
has been rubbed by woollen, they attract each other ; 
hence it is said, that bodies similarly electrified repel 
each other, and bodies dissimilarly electrified attract 
each other : and the electricity of glass is called 
vitreous or positive electricity, and that of sealing-wax 
resinous or negative electricity. 

When of two bodies made to rub each other one 
is found positively electrified, the other is always 
found negatively electrified, and, as in the common 
electrical machine, these states are capable of being 
communicated to metals placed upon rods or pillars of 
glass. Electricity is produced likewise by the contact 
of bodies ; thus a piece of zinc and of silver give a 
slight electrical shock when they are made to touch 
each other, and to touch the tongue : and when a 
number of plates of copper and zinc, 100 for instance, 
are arranged in a pile with cloths moistened in salt and 
water, in the order of zinc, copper, moistened cloth, 
zinc, copper, moistened cloth, and so on, they form 
an electrical battery which will give strong shocks 



C 37 3 

and sparks, and which is possesed of remarkable 
chemical powers. The luminous phasnomena pro- 
duced by common electricity are well known. It 
would be improper to dwell upon them in this 
place. They are the most impressive effects occa- 
sioned by this agent ; and they offer illustrations 
of lightning and thunder. 

Electrical changes are constantly taking place in 
nature, on the surface of the earth and in the atmos- 
phere ; but as yet the effects of this power in vegeta- 
tion have not been correctly estimated. It has been 
shewn by experiments made by means of the Voltaic 
battery (the instrument composed of zinc, copper, and 
water), that compound bodies in general are capable 
of being decomposed by electrical powers, and it is 
probable, that the various electrical phasnomena oc- 
curring in our system, must influence both the ger- 
mination of seeds and the growth of plants. I found 
that corn sprouted much more rapidly in water posi- 
tively electrified by the Voltaic instrument than in 
water negatively electrified ; and experiments made 
upon the atmosphere shew that clouds are usually ne- 
gative ; and as when a cloud is in one state of elec- 
tricity the surface of the earth beneath is brought into 
the opposite state, it is probable that in common cases 
the surface of the earth is positive. 

Different opinions are entertained amongst scien- 
tific men respecting the nature of electricity ; by some, 
the phasnomena are conceived to depend upon a single 
subtile fluid in excess in the bodies said to be posi- 
tively electrified, in deficiency in the bodies said to be 



I 33 2 

negatively electrified, A second class suppose the 
effects to be produced by two different fluids, called 
by them the vitreous fluid and the resinous fTuid ; and 
others regard them as affections ar motions of matter, 
or an exhibition of attractive powers, similar to those 
which produce chemical combination and decomposi- 
tion ; but usually exerting their action on masses. 

The different powers that have been thus gener- 
ally described, continually act upon common matter 
so as to change its form and produce arrangements 
fitted for the purposes of life. Bodies are either sim- 
ple or compound. A body is said to be simple, when 
it is incapable of being resolved into any other forms 
of matter. Thus gold, or silver, though they may 
be melted by heat or dissolved in corrosive menstrua, 
yet are recovered unchanged in their properties, and 
they are said to be simple bodies. A body is consi- 
dered as compound, when two or more distinct sub- 
stances are capable of being produced from it ; thus 
marble is a compound body, for by a strong heat, it is 
converted into lime, and an elastic fluid is disengaged 
in the process : and the^roof of our knowledge of 
the true composition of a body is, that it is capable of 
being reproduced by the same substances as those into 
which it had been decomposed ; thus by exposing 
lime for a long while to the elastic fluid, disengaged 
during its calcination, it becomes converted into a sub- 
stance similar to powdered marble. The term element 
has the same meaning as simple or undecompounded 
body ; but it is applied merely with reference to the 
present state of chemical knowledge. It is probable, 



[39 ] 

that as yet we are not acquainted with any of the true 
elements of matter ; many substances, formerly sup- 
posed to be simple, have been lately decompounded, 
and the chemical arrangement of bodies must be con- 
sidered as a mere expression of facts, the results of 
accurate statical experiments. 

Vegetable substances in general are of a very 
compound nature, and consist of a great number of 
elements, most of which belong likewise to the other 
kingdoms of nature, and are found in various forms. 
Their more complicated arrangements are best under- 
stood after their simpler forms of combination have 
been examined. 

The number of bodies which I shall consider as 
at present undecomposed, are, as was stated in the 
introductory lecture, two gasses that support combus- 
bustion, seven inflammable bodies, and thirty-eight 
metals. 

In most of the inorganic compounds, the nature 
of which is well known, into which these elements 
enter, they are combined in definite proportions ; so 
that if the elements be represented by numbers, the 
proportions in which they combine are expressed 
either by those numbers, or by some simple multiples 
of them. 

I shall mention, in few words, the characteristic 
properties of the most important simple, substances, 
and the numbers representing the proportions in 
which they combine in those cases, where they haVe 
been accurately ascertained. 



L 40 3 

1. Oxygene forms about one-fifth of the air of our 
atmosphere. It is an elastic fluid, at all known tem- 
peratures. Its specific gravity is to that of air as 10967 
to 10000. It supports combustion with much more 
vividness than common air ; so that if a small steel 
wire, or a watch spring, having a bit of inflamed wood 
attached to it, be introduced into a bottle filled with 
the gas, it burns with great splendour. It is respirable. 
It is very slightly soluble in water. The number re- 
presenting the proportion in which it combines is 15. 
It may be made by heating a mixture of the mineral 
called manganese, and sulphuric acid together, in a 
proper vessel, or by heating strongly red lead,- or red 
precipitate of mercury. 

2. Chlorine, or oxymuriatic gas, is like oxygene, a 
permanent elastic fluid. Its colour is yellowish green, 
its smell is very disagreeable ; it is not respirable ; it 
supports the combustion of all the common inflam- 
mable bodies except charcoal ; its specific gravity 
is to that of air as 24677 to 10000 ; it is soluble 
in about half its volume of water, and its solution in 
water destroys vegetable colours. Many of the 
metals (such as arsenic or copper) take fire spon- 
taneously when introduced into a jar or bottle filled 
with the gas. Chlorine may be procured by heating 
together a mixture of spirits of salt or muriatic acid, 
and manganese. The number representing the pro- 
portion in which this gas enters into combination 
is 67. 

3. Hydrogene, or inflammable air, is the lightest 
known substance ; its specific gravity is to that of air 



C *i D 

as 732 to 10000. It burns by the action of an in- 
flamed taper, when in contact with the atmosphere. 
The proportion in which it combines is represented by 
unity, or 1. It is procured by the action of diluted oil 
of vitriol, or hydro sulphuric acid on filings of zinc or 
iron. It is the substance employed for filling air bal- 
loons. 

4. Azote is a gaseous substance not capable of 
feeing condensed by any known degree of cold : its 
specific gravity is to that of common air as 95 1 6 to 
10000. It does not enter into combustion under 
common circumstances, but may be made to unite 
with oxygene by the agency of electrical iive. It forms 
nearly four fifths of the air of the atmosphere ; and 
may be procured by burning phosphorus in a confin- 
ed portion of air. The number representing the pro- 
portion in which it combines is 26. 

5. Carbon is considered as the pure matter of 
charcoal, and it may be produced by passing spirits of 
wine through a tube heated red. It has not yet been 
fused ; but rises in vapour at an intense heat. Its 
specific gravity cannot be easily ascertained ; but that 
of the diamond, which cannot chemically be distin- 
guished from pure carbon, is to that of water as 3500 
to 1000. Charcoal has the remarkable property of 
absorbing several times its volume of different elastic 
fluids which are capable of being expelled from it by 
heat. The number representing it is 11.4. 

6. Sulphur is the pure substance so well known 
by that name : its specific gravity is to that of water 
as 1990 ro lOOO. It fuses at about 220° Fahrenheit ; 

G 



C 42 ] 

and at between 500° and 600" takes fire, if in contact 
with the air, and burns with a pale blue flame. In this 
process it dissolves in the oxygene of the air, and pro- 
duces a peculiar acid elastic fluid. The number re- 
presenting it is 30. 

7. Phosphorus is a solid of a pale fed colour, of 
specific gravity 1770. It fuses at 90", and boils at 
.550°. It is luminous in the air at common tempera- 
tures, and burns with great violence at 150°, so that 
it must be handled with great caution. The number 
representing it is 20. It is procured by digesting 
together bone ashes and oil of vitriol, and strongly 
heating the fluid substance so produced with powdered 
charcoal. 

8. Boron is a solid of a dark olive colour, infu- 
sible at any known temperature. It is a substance 
very lately discovered, and procured from boracic 
acid. It burns with brilliant sparks, when heated in 
oxygene, but not in chlorine. Its specific gravity, 
and the number representing it, are not yet accurately 
known. 

9. Platinum is one of the noble metals, of rather 
a duller white than silver, and the heaviest body in 
nature ; its specific gravity being 2 1 500. It is not 
acted upon by any acid menstrua except such as con- 
tain chlorine : It requires an intense degree of heat 
for its fusion. 

10. The properties of gold are well known. Its 
specific gravity is 19277. It bears the same relation 
to acid menstrua as platinum : it is one of the char- 
acteristics of both these bodies, that they are very dif- 
cuUly acted upon by sulphur. 



C 4s 1 

11. Silver is of specific gravity 1O400, it burns 
more readily than plantinum or gold, which require 
the intense heat of electricity. It readily unites to 
sulphur. The number representing it is 205. 

12. Mercury is the only known metal fluid at 
the common temperature of the atmosphere ; it boils 
at 66 °, and freezes at 39° below 0. Its specific gra- 
vity is 1356 \ The number representing it is 380. 

13 Copper is of specific gravity 8890. It burns 
when strongly heated with red flame tinged with 
green. The number representing it is 1 20. 

14. Cobalt is of specific gravity 7^00. Its point 
of fusion is very high, nearly equal to that of iron. 
In its calcined or oxidated state, it is employed for 
giving a blue colour to glass. 

15. Nickel is of a white colour : its specific gra- 
vity is 8820. This metal and cobalt agree with iron, in 
being attractible by the magnet. The number repre- 
senting nickel is 111. 

16. Iron is of specific gravity 7700. Its other 
properties are well known. The number represent- 
ing it is 103. 

17. Tin is of specific gravity 7291 ; it is a very 
fusible metal, and burns when ignited in the air : the 
aumber representing the proportion in which it com- 
bines is 110. 

18. Zinc is one of the most combustible of the 
common metals. Its specific gravity is about 7210. 
It is brittle metal under common circumstances ; but 
when heated may be hammered or rolled into thin 
leaves, and after this operation is malleable. The num- 
ber representing it is 66* 



L 44 ] 

19. Lead is of specific gravity 11352 ; it fuset 
at a temperature rather higher than tin. The num- 
ber representing it is 398. 

20. Bismut/j is a brittle metal of specific gravity 
9822. It is nearly as fusible as tin ; when cooled 
slowly it crystallizes in cubes. The number repre- 
senting it is 1 35. 

21. Antimony is a metal capable of being volat- 
ilized by a strong red heat. Its specific gravity is 
6800. It burns when ignited with a faint white light. 
The number representing it is 170. 

22. Arsenic is of a blueish white colour, of 
specific gravity 8310. It may be procured by heating 
the powder of common white arsenic of the shops 
xtrongly in a Florence flask with oil. The metal rises 
in vapour, and condenses in the neck of the flask. 

The number representing it is 90. 

23. Manganeswn may be procured from the 
mineral called manganese, by intensely igniting it in 
a forge mixed with charcoal powder. It is a metal 
very difficult of fusion, and very combustible ; its 
specific gravity is 6850. The number representing it 
is 177. 

24. Potassium is the lightest known metal, being 
only of specific gravity 850. It fuses at about 150°, 
and rises in vapour at a heat a little below redness, 
It is a highly combustible substance, takes fire when 
thrown upon water, burns with great brilliancy, and 
the product of its combustion dissolves in the water. 
The number representing it is 75. It may be made 
by passing fused caustic vegetable alkali, (the pure kali 



C 4o 3 

of druggists) through iron turnings strongly ignited 
in a gun barrel, or by the electrization of potash by a 
strong Voltaic battery. 

25. Sodium may be made in a similar manner to 
potassium. Soda or the mineral alkali being substituted 
for the vegetable alkali. It is of specific gravity 940. 
It is very combustible. When thrown upon water, 
it swims on its surface, hisses violently, and dissolves, 
but does not inflame. The number representing it 
is 88. 

26. Barium has as yet been procured only by 
electrical powers and in very minute quantities, so that 
its properties have not been accurately examined. 
The number representing it appears to be 1 30. 

Strontium the 27th, Calcium the 28th, Mag}2esiwn 
the 29th, Silicw?i the 30th, Aluminu?n the 3 1st, Zir- 
conu7n the 32d, Glucinurn the 33d, and Ittrium the 
34th of the undecompounded bodies, like barium, 
have either not been procured absolutely pure, or 
only in such minute quantities that their properties 
are little known ; they are formed either by electrical 
powers, or by the agency of potassium, from the dif- 
ferent earths whose names they bear, with the change 
of the termination in u?n ; and the numbers repre- 
senting them are believed to be 90 strontium, 40 cal- 
cium, 38 magnesium, 31 silicum, 33 aluminum, 70 
zirconum, 39 glucinum, 1 1 1 ittrium. 

Of the remaining thirteen simple bodies, twelve 
are metals, most of which, like those just mentioned, 
can only be procured with very great difficulty ; and 
the substances in general from which they are procur-~ 



C 46 ] 

ed are very rare in nature. They are Palladiiony 
Rhodium, Osmium, Iridium, Colubium, Chromium, Mo- 
lybdenu?n. Cerium^ Tellurium, Tungstenum, Titanium, 
Uranium. The forty-seventh body has not as yet 
been produced in a state sufficiently pure to admit 
of a minute examination. It is the principle which 
gives character to the acid called fluoric acid, and 
may be named Fluon, and is probably analogous to 
phosphorus or sulphur. The numbers representing 
these last thirteen bodies have not yet been determin- 
ed with sufficient accuracy to render a reference to 
them of any utility. 

The undecompounded substances unite with each 
other, and the most remarkable compounds are form- 
ed by the combinations of oxygene and chlorine with 
inflammable bodies and metals ; and these combina- 
tions usually take place with much energy, and are 
associated with fire. 

Combustion in fact, in common cases, is the 
process of the solution of a body in oxygene, as hap- 
pens when sulphur or charcoal is burnt ; or the fixa- 
tion of oxygene by the combustible body in a solid 
form, which takes place when most metals are burnt, 
or when phosphorus inflames ; or the production of 
a fluid from both bodies, as when hydrogene and oxy- 
gene unite to form water. 

When considerable quantities of oxygene or of 
chlorine unite to metals or in^ammable bodies, they 
often produce acids : thus sulphureous, phosphoric, 
and boracic acids are formed by a union of considera- 
ble quantities of oxygene with sulphur, phosphorus. 



C 47 J 

and boron : and muriatic acid gas is formed by the 
union of chlorine and hydrogene. 

When smaller quantities of oxygene or chlorine 
unite with inflammable bodies or metals, they form 
substances not acid, and more or less soluble in wa- 
ter ; and the metallic oxides, the fixed alkalies, and 
the earths, all bodies connected by analogies ; are pro- 
duced by the union of metals with oxygene. 

The composition of any compounds, the nature 
of which is well known, may be easily learnt from the 
numbers representing their elements ; all that is ne- 
cessary, is to know how many proportions enter into 
union. Thus potassa, or the pure caustic vegetable 
alkali, consists of one proportion of potassium and one 
of oxygene, and its constitution is consequently 75 
potassium, 15 oxygene. 

Carbonic acid is composed of two proportions of 
oxygene 30, and one of carbon 11.4. 

Again, lime consists of one proportion of calcium 
and one of oxygene, and it is composed of 40 of cal- 
cium and 1 5 of oxygene. And carbonate of lime, or 
pure chalk, consists of one proportion of carbonic 
acid 41.4, and one of lime 55. 

Water consists of two proportions of hydrogene 
2, and one of oxygene 1 5 ; and when water unites to 
other bodies in definite proportions, the quantity is 1 7, 
or some multiple of 17, i. e. 34 or 51, or 68, &c. 

Soda, or the mineral alkali, contains two propor- 
tions of oxygene to one of sodium. 

Ammonia, or the volatile alkali is composed of six 
proportions of hydrogene and one of azote. 



C 48 ] 

Amongst the earths, Silica or the earth of flints, 
probably consists of two proportions of oxygene to 
one of silicum ; and Magnesia, Strontia, Baryta or 
Baryta, Alumina, Zircona, Glusina, and Ittria of one 
proportion of metal and one of oxygene. 

The metallic oxides in general consist of the metals 
united to from one to four proportions of oxygene ; 
and there are, in some cases, many different oxides of 
the same metal ; thus there are three oxides of lead ; 
the yellow oxide, or massicot, contains two proportions 
of oxygene ; the red oxide, or ?nimwn, three ; and the 
puce coloured oxide four proportions. Again there are 
two oxides of copper, the black and the orange ; the 
black contains two proportions of oxygene, the 
orange one. 

For pursuing such experiments on the composi- 
tion of bodies as are connected with agricultural che- 
mistry, a few only of the undecompounded substan- 
ces are necessary ; and amongst the compounded 
bodies, the common acids, the alkalies, and the earths, 
are the most essential substances. The elements 
found in vegetables, as has been stated in the intro- 
ductory lecture, are very few. Oxygene, hydrogene, 
and carbon constitute the greatest part of their organ- 
ized matter. Azote, phosphorus, sulphur, mangane- 
sum, iron, silicum, calcium, aluminum, and magne- 
sium likewise, in different arrangements, enter into 
their composition, or are found in the agents to which 
they are exposed ; and these twelve undecompound- 
ed substanceijv are the elements, the study of which 
is of the most importance to the agricultural chemist. 



C 49 ] 

The doctrine of definite combinations, as will be 
shewn in the following lectures, will assist us in gain- 
ing just views respecting the composition of plants, 
and the economy of the vegetable kingdom ; but the 
same accuracy of weight and measure, the same statical 
results which depend upon the uniformity of the laws 
that govern dead matter, cannot be expected in opera- 
tions where the powers of life are concerned, and 
where a diversity of organs and of functions exists. 
The classes of definite inorganic bodies, even if we 
include all the crystalline arrangements of the mineral 
kingdom, are few, compared with the forms and sub- 
stances belonging to animated nature. Life gives a 
peculiar character to all its productions ; the power of 
attraction and repulsion, combination and decomposi- 
tion, are subservient to it ; a few elements, by the 
diversity of their arrangement, are made to form the 
most different substances ; and similar substances are 
produced from compounds which, when superficially 
examined, appear entirely different. 



H 



50 



LECTURE 111. 

On the Organization of Plajits. Of the Roots ^ Trunks 
and Branches, Of their Structure. Of the Epider- 
mis. Of the cortical and alb ur nous Parts of Leaves^ 
Flowers^ and Seeds. Of the chejuical Constitution of 
the Organs of Plafits, and the Substances found in 
them. Of mucilaginous^ saccharine^ extractive ^resin* 
ous^ and oily. Substances^ and other vegetable Com" 
pounds, their Arrangements in the Organs of Plants^ 
their Co??iposition, Changes, and Uses. 

VARIETY characterises the vegetable kingdom, 
yet there is an analogy between the forms and the 
functions of all the different classes of plants, and on 
this analogy the scientific principles relating to their 
organization depend. 

Vegetables are living structures distinguished 
from animals by exhibiting no signs of perception, 
or of voluntary motion ; and their organs are either 
organs of nourishment or of reproduction ; organs 
for the preservation and increase of the individual, or 
for the multiplication of the species. 

In the living vegetable system there are to be 
considered, the exterior form, and the interior consti- 
tution. 

Every plant examined as to external structure, 
displays at least four systems of organs — or some 
analogous parts. First, the Root. Secondly, the 



I -1 3 

Trunk and Branches, or Stein. Thirdly, the Leaves ; 
and, fourthly, the Flowers or Seeds. 

The root is that part of the vegetable which least 
impresses the eye ; but it is absolutely necessary. It 
attaches the plant to the surface, is its organ of nour- 
ishment, and the apparatus by which it imbibes food 
from the soil. — The roots of plants, in their anatomi- 
cal division, are veiy similar to the trunk and 
branches. The root may indeed be said to be a con- 
tinuation of the trunk terminating in minute ramifica- 
tions and filaments, and not in leaves ; and by bury- 
ing the branches of certain trees in the soil, and eleva- 
ting the roots in the atmospheae, there is, as it were, 
an inversion of the functions, the roots produce buds 
and leaves, and the branches shoot out into radical 
fibres and tubes. This experiment was made by 
Woodward on the willow, and has been repeated by 
a number of physiologists. 

When the branch or the root of a tree is cut 
transversely, it usually exhibits three bodies : the bark, 
the wood, and the pith ; and these again are individu- 
ally susceptible of a new division. 

The bark, when perfectly formed, is covered by 
a thin cuticle or epidennis, which may be easily separ- 
ated. It is generally composed of a number of laminae 
or scales, which in old trees are usually in a loose and 
decaying state. The epidermis is not vascular, and it 
merely defends the interior parts from injury. In 
forest trees, and in the larger shrubs, the bodies of 
which are firm, and of strong texture, it is a part of 
little importance j but in the reeds, the grasses, canes^ 



C 52 3 

arid the plants having hollow stalks, it is of great use, 
and is exceedingly strong, and in the microscope seems 
composed of a kind of glassy net-work, which is prin- 
cipally siliceous earth. 

This is the case in wheat, in the oat, in different 
speci s of equisetum, and, above all, in the rattan, the 
epidermis of which contains a sufficient quantity of 
flint to give light when struck by steel ; or two pieces 
rubbed together produce sparks. This fact first oc- 
curred to me in 1798, and it led to experiments, by 
which I ascertained that siliceous earth existed gener- 
ally in the epidermis of the hollow plants. 

The siliceous epidermis serves as a support, pro- 
tects the bark from the action of insects, and seems 
to perform a part in the economy of these feeble ve- 
getable tribes, similar to that performed in the animal 
kingdom by the shell of the crustaceous insects. 

Immediately beneath the epidermis i» the paren- 
chyma. It is a soft substance consisting of cells filled 
with fluid, having almost always a greenish tint. The 
cells in the parenchymatous part, when examined by 
the microscope, appear hexagonal. This form, in- 
deed, is that usually affected by the cellular mem- 
branes in vegetables, and it seems to be the result of 
the general re-action of the solid parts, similar to that 
which takes place in the honey-comb. This arrange- 
ment, which h^s usually been ascribed to the skill and 
artifice of the bee, seems, as Dr. Wollaston has ob- 
served, to be merely the result of the mechanical laws 
which influence the pressure of cylinders composed of 
soft materials, the nests of solitary bees being uni- 
formly circular. 



C 53 3 

The innermost part of the bark is constituted by 
the cortical layers^ and their numbers vary with the age 
of the tree. On cutting the bark of a tree of several 
years standing, the productions of different periods 
may be distinctly seen, though the layer of every 
particular year can seldom be accurately defined. 

The cortical layers are composed of fibrous parts 
which appear interwoven, and which are transverse 
and longitudinal. The transverse are membranous 
and porous, and the longitudinal are generally com- 
posed of tubes. 

The functions of the parenchymatous and cortical 
parts of the bark are of great importance. The tubes 
of the fibrous parts appear to be the organs that re- 
ceive the sap ; the cells seem destined for the elabora- 
tion of its parts, and for the exposure of them to the 
action of the atmosphere, and the new matter is annu- 
ally produced in the spring, immediately on the inner 
surface of the cortical layer of the last year. 

It has been shewn by the experiments of Mr. 
Knight, and those made by other physiologists, that 
the sap descending through the bark after being 
modified in the leaves, is the principal cause of th6 
growth of the tree ; thus, if the bark is wounded, the 
principal formation of new bark is on the upper edge 
of the wound j and when the wood has been removed, 
the formation of new wood takes place immediately 
beneath the bark : yet it would appear from the late 
observations of M. Palisot de Beauvois, that the sap 
may be transferred to the bark, so as to exert its nutri- 
tive functions, independent of any general system of 



C -54 ] 

circulation. That gentleman separated different por- 
tions of bark from the rest of the bark in several trees, 
and found that in most instances the separated bark 
grew in the same manner as the bark in its natural 
state. The experiment was tried with most success 
on the lime-tree, the maple and the lilac ; the layers of 
bark were removed in August 1810, and in the spring 
of the next year, in the case of the maple and the lilac> 
small annual shoots where produced in the parts 
where the bark was insulated.* 

The wood of trees is composed of an external or 
living part, called alburnum or sap-wood, and of an in- 
ternal and dead part, the heart-wood. The alburnum 
is white, and full of moisture, and in young trees and 
annual shoots it reaches even to the pith. The albur- 
num is the great vascular system of the vegetable 
through which the sap rises, and the vessels in it ex- 
tend from the leaves to the minutest filaments in the 
roots. 

There is in the alburnum a membranous sub- 
stance composed of cells, which are constantly filled 
with the sap of the plant, and there are in the vascu- 
lar system several different kinds of tubes ; Mirbel has 
distinguished four species, the simple tubes, the porous 
tubes, the trachea, and the false trache.f.f 

The tubes, which he has called simple tubes, 
seem to contain the resinous or oily fluids peculiar to 
diflerent plants. 



• Fig. 3 represents the result of the experiment on the maple. Journal de 
Physique, September nil, page 210. 

t Fig. 4, 5, 6, and 7, represent Mirbel's idea of the simple tufies, the porous 
tubes, the tracheje, and the false trachea. 



p. 34 







Fiq.3. 




^\^4- 




Fig: 8. 



p-3^- 



Fig 9 




Fig: lo. 




[ 55 3 

The porous tubes likewise contain these fluids ; 
and their use is probably that of conveying them into 
the sap for the production of new arrangements. 

The tracheas contain fluid matter, which is al- 
ways thin, watery, and pellucid, and these organs, 
as well as the false tracheas, probably carry off water 
from the denser juices, which are thus enabled to con- 
solidate for the production of new wood. 

In the arrangement of the fibres of the wood, 
there are two distinct appearances. There are series 
of white and shining laminae which shoot from the 
centre towards the circumference, and these constitute 
what is called the silver grain of the wood. 

There are likewise numerous series of concentric 
layers which are usually called the spurious grain, and 
their number denotes the age of the tree.* 

The silver grain is elastic and contractile, and it 
has been supposed by Mr. Knight, that the change of 
volume produced in it by change of temperature Js 
one of the principal causes of the ascent of the sap. 
The fibres of it seem always to expand in the morning 
and contract at night ; and the ascent of the juices, as 
was stated in the last Lecture, depends principally on 
the agency of heat. 

The silver grain is most distinct in forest trees ; 
but even annual shrubs have a system of fibres simi- 
lar to it. The analogy of nature is constant and uni- 



• Fig. 8 represents the section of an elm branch, which exhibits the tubular 
structure and the silver and spurious grain. Fig. 9 represents the section of pars 
of the branch of juv oak, fig. lo, that of the branch of an ash. 



[ 56 ] 

form, and similar effects are usually produced by simi- 
lar organs. 

The pith occupies the centre of the wood ; its 
texture is membranous ; it is composed of cells, which 
are circular towards the extremity, and hexagonal in 
the centre of the substance. In the first infancy of 
the vegetable, the pith occupies but a small space. It 
gradually dilates, and in annual shoots and young 
trees offei"s a considerable diameter. In the more 
advanced age of the tree, acted on by the heart-wood, 
pressed by the new layers of the alburnum, it begins 
to diminish, and in very old forest trees disappears 
altogether. 

Many different opinions have prevailed with re- 
gard to the use of the pith. Dr. Hales supposed, that 
it was the great cause of the expansion and develope- 
ment of the other parts of the plant ; that being the 
most interior, it was likewise the most acted upon of 
all the organs, and that from its reaction the pheno- 
mena of their developement and growth resulted. 

Linnaeus, whose lively imagination was continu- 
ally employed in endeavours to discover analogies be- 
tween the animal and vegetable systems, conceived 
" that the pith performed for the plant the same func- 
tions as the brain and nerves in animated beings." He 
considered it as the organ of irritability, and the seat 
of life. 

The latest discoveries have proved, that these two 
opinions are equally erroneous. Mr. Knight has re- 
moved the pith in several young trees, and they con- 
tinued to live and to increase. 



It is evidently then only an organ of secondary 
importance. In early shoots, in vigorous growth, it is 
filled with moisture, and it is a reservoir, perhaps, of 
fluid nourishment at the time it is mosi wanted. As 
the heart-wood forms, it is more and more separated 
from the living part, the alburnum ; its functions be- 
come extinct, it diminishes, dies, and last disappears. 
The toidrih, the spines, and other similar parts 
of plants are analogous in their organization to the 
branches, and offer a similar cortical and alburnous 
organization. It has been shown, by the late obser- 
vations of Mr. Knight, that the directions of tendrils, 
and the spiral form they assume, depend upon the 
unequal action of light upon them, and a similar 
reason has been assigned by M. Decandolle to account 
for the turning of the parts of plants towards the sun ; 
that ingenious physiologist supposes that the fibres 
are shortened by the chemical agency of the solar 
rays upon them, and that, consequently, the parts 
will move towards the light. 

The leaves, the great sources of the permanent 
beauty of vegetation, though infinitely diversified in 
their forms, are in all cases similar in interior organi- 
zation, and perform the same functions. 

The alburnum spreads itself from the foot-stalks 
into the very extremity of the leaf ; it retains its vas- 
cular system and its living powers ; and its peculiar 
tubes, particularly the tracheas, may be distinctly seen 
In the leaf.* 



• Fig 11. represents part of a leaf of a vine magnified and cut, so as to e\bi. 
bit the traches ; it \z copied, as are also the preceding; figures, from Grew's Aii.i- 
tomy of Plants. 

I* 



C $s 3 

The green membranous substance may be consi- 
dered as an extension of the parenchyma, and the 
fine and thin covering as the epidermis. Thus the 
organization of the roots and branches may be traced 
into the leaves, v/hich present, however, a more per- 
fect, refined, and minute structure. 

One great use of the leaves is, for the exposure 
of the sap to the influence of the air, heat, and light. 
Their surface is extensive, the tubes and cells 
very delicate, and their texture porous and trans- 
parent. 

In the leaves much of the water of the sap is 
evaporated ; it is combined with new principles, and 
fitted for its organizing functions, and probably pas- 
ses, in its prepared state, from the extreme tubes of 
the alburnum into the ramifications of the cortical 
tubes and then descends through the bark. 

On the upper surface of leaves, which is expos- 
ed to the sun, the epidermis is thick but transparent, 
and is composed of matter possessed of little organi- 
zation, which is either principally earthy, or consists 
of some homogeneous chemical substance. In the 
grasses it is partly siliceous, in the laurel resinous, 
and in the maple and thorn, it is principally constitut- 
ed by a substance analogous to wax. 

By these arrangements any evaporation, except 
from the appropriated tubes, is prevented. 

On the lower surface the epidermis is a thin 
transparent membrane full of cavities, and it is proba- 
bly altogether by this surface that moisture and the 
principles of the atmosphere necessary to vegetation 
are absorbed. 



C 59 ] 

If a leaf be turned, so as to present its lower sur- 
face to the sun, its fibres will twist so as to bring it as 
much as possible into its original position ; and all 
leaves elevate themselves on the foot-stalk during their 
exposure to the solar light, and as it were moved to- 
wards the sun. 

This effect seems in a great measure dependent 
upon the mechanical and chemical agency of light and 
heat. Bonnet made artificial leares, which, when a 
moist sponge was held under the lower surface, and 
a heated iron above the upper surface, turned exactly 
in the same manner as the natural leaves. This how- 
ever can be considered only as a very rude imitation 
of the natural process. 

What Linnaeus has called the sleep of the leaves, 
appears to depend wholly upon the defect of the ac- 
tion of light and heat, and the excess of the operation 
of moisture. 

This singular but constant phenomenon had 
never been scientifically observed, till the attention of 
the botanist of Upsal was fortunately directed to it. 
He was examining particularly a species of lotus, in 
which four flowers had appeared during the day, and 
he missed two in the evening j by accurate inspection, 
he soon discovered that these two were hidden by the 
leaves which had closed round them. Such a circum- 
stance could not be lost upon so acute an observer. 
He immediately took a lantern, went into his garden, 
and witnessed a series of curious facts before un- 
known. All the simple leaves of the plants he exam- 
ined, had an arrangement totally different from their 



C 60 ] 

arrangement In the day : and the greater number of 
them were seen closed or folded together. 

The sleep of leaves is, in some cases, capable of 
being produced artificially. Decandolle made this ex- 
periment on the sensitive plant. By confining it in 
a dark place in the day time, the leaves soon closed j 
but on illuminating the chamber with many lamps, 
they again expanded. So sensible were they to the 
effects of light and radiant heat. 

In the greater number of plants the leaves annu- 
ally decay, and are reproduced ; their decay takes place 
either at the conclusion of the summer, as in very hot 
climates, when they are no longer supplied with sap, 
in consequence of the dryness of the soil, and the 
evaporating powers of heat ; or in the autumn, as in 
the northern cHmates at the commencement of the 
frosts. The leaves preserve their functions in com- 
mon cases no longer than there is a circulation of 
fluids through them. In the decay of the leaf, the 
. colour assumed seems to depend upon the nature of 
the chemical change, and as acids are generally devel- 
oped, it is usually^ either reddish brown or yellow ; 
yet there are great varieties. Thus in the oak, it is 
bright brown ; in the beech, orange ; in the elm, yel- 
low ; in the vine, red ; in the sycamore, dark brown ; 
in the cornel tree, purple ; and in the woodbine, blue. 

The cause of the preservation of the leaves of 
evergreens through the winter is not accurately 
known. From the experiments of Hales, it appears 
that the force of the sap is much less in plants of this 
species, and probably there is a certain degree of circii- 



C ci J 

iation throughout the winter ; their juices are less wa- 
tery than those of other plants, and probably less liable 
to be congealed by cold, and they are defended 
by stronger coatings from the action of the 
elements. 

The production of the other parts of the plant 
takes place at the time the leaves are most vigorously 
performing their functions. If the leaves are stripped 
off from a tree in spring, it uniformly dies, and when 
many of the leaves of forest trees are injured by 
blasts, the trees always become stag-headed and un- 
healthy. 

The leaves are necessary for the existence of the 
individual tree, the Jlowers for the continuance of the 
species. Of all the parts of plants they are the most 
refined, the most beautiful in their structure, and ap- 
pear as the master-work of nature in the vegetable 
kingdom. The elegance of their tints, the variety of 
their forms, the delicacy of their organization, and 
the adaptation of their parts, are all calculated to 
awaken our curiosity, and excite our admiration. 

In the flower there are to be observed, 1st, the 
calyx, or green membranous part forming the support 
for the coloured floral leaves. This is vascular, and 
agrees with the common leaf in its texture and organi- 
zation ; it defends, supports, and nourishes the more 
perfect parts. 2d. The corolla, which consists either 
of a single piece, when it is called monopetalous, or of 
many pieces, when it is called polypetalous. It is 
usually very vivid in its colours, is filled with an al- 
most infinite variety of small tubes of the porous kind j 



L" 6^ J 

it incloses and defends the essential parts in the inte- 
rior, and supplies the juices of the sap to them. These 
parts are, 3d, the stamens and the pistils* 

The essential part of the stamens are the sum- 
mits or anthers, which are usually circular and of a 
highly vascular texture, and covered with a fine dust 
called the pollen. 

The pistil is cylindrical, and surmounted ^y the 
style ; and top of which is generally round and pro- 
tuberant.* 

In the pistil, when it is examined by the micro- 
scope, congeries of spherical forms may usually be 
perceived, which seem to be the bases of the future 
seeds. 

It is upon the arrangement of the stamens and 
the pistils, that the Linnean classification is founded. 
The numbers of the stamens and pistils in the same 
flower, their arrangements, or their division in differ- 
ent flowers, are the circumstances which guided the 
Swedish philosopher, and enabled him to form a sys- 
tem admirably adapted to assist the memory, and ren- 
der botany of easy acquisition ; and which, though it 
does not always associate together the plants most 
analogous to each other in their general characters, is 
yet so ingeniously contrived as to denote all the analo- 
gies of their most essential parts. 

The pistil is the organ which contains the rudi- 
ments of the seed ; but the seed is never formed as a 



* Fig. 12 represents the common Uliy, a, the eoio'.la, Ibbbh, rhe anthers. 
CI the pistil, 



[ 63 ] 

reproductive germ, without the influence of the poilen, 
or dust on the anthers. 

This mysterious impression is necessary lo the 
continued succession of the different vegetable tribes. 
It is a feature which extends the resemblances of the 
different orders of beings, and estabhshes, on a great 
scale, the beautiful analogy of nature. 

The ancients had observed, that different date 
trees bore different flowers, and that those trees pro- 
ducing flowers which contained pistils bore no fruit, 
unless in the immediate vicinity of such trees as pro- 
duced flowers containing stamens. This long esta- 
blished fact strongly impressed the mind of Malpighi, 
who ascertained several analogous facts with regard to 
other vegetables. Grew, however, was the first per- 
son who attempted to generalize upon them, and 
much just reasoning on the subject may be found in 
his works. Linnasus gave a scientific and distinct 
form to that which Grew had only generally observ- 
ed, and has the glory of establishing what has been 
called the sexual system, upon the basis of minute ob- 
servations and accurate experiments. 

The seed, the last production of vigorous vegeta- 
tion, is wonderfully diversified in form. Being of the 
highest importance to the resources of nature, it is 
defended above all other parts of the plant j by soft 
pulpy substances, as in the esculent fruits, by thick 
membranes, as in the leguminous vegetables, and by 
hard shells, or a thick epidermis, as in the palms an4 
grasses. 



[ G4. ] 

In every seed there is to be distinguished, 1, the 
crgan of nourishment ; 2, the nascent plant, or the 
flume ; 3, the nascent root, or the radicle. 

In the common garden bean, the organ of nour- 
ij^Iiment is divided into two lobes called cotyledons ; the 
plume is the small white point between the upper 
part of the lobes ; and the radicle is the small curved 
cone at.their base.* 

In wheat, and in many of the grasses, the organ 
of nourishment is a single part, and these plants are 
called ?nonocotyicdonous. In other cases it consists of 
more than two parts, when the plants are called poly- 
cotyledonous. In the greater number of instances, it 
is, however, simply divided into two, and is dicotyle- 
donous. 

The matter of the seed, when examined in its 
common state, appears dead and inert ; it exhibits 
neither the forms nor the functions of life. But let 
it be acted upon by moisture, heat, and air, and its 
organized powers as'e soon distinctly developed. The 
cotyledons expand, the membranes burst, the radicle 
acquires new matter, descends into the soil, and the 
plume rises towards the free air. By degrees, the 
organs of nourishment of dicotyledonous plants be- 
come vascular, and are converted into seed leaves, 
and the perfect plant appears above the soil. Nature 
has provided the elements of germination on every 
part of the surface j water and pure air and heat are 



• Fig. 13, represents the garden bean, aa, the cotyledons, h, the plume, c, the 
radicle. 



p. 64 







Fuf.lt. 





i: 65 3 

universally active, and the means for the preserva- 
tion and multiplication of life, are at once simple and 
grand. 

To enter into more minute details on the vegetable 
physiology would be incompatible with the objects of 
these Lectures. I have attempted only to give such 
general ideas on the subject, as may enable the philo- 
sophical agriculturist to understand the functions of 
plants ; those who wish to study the anatomy of ve- 
getables, as a distinct science, will find abundant ma- 
terials in the works of the authors I have quoted, 
page 9, and likewise in the writings of Linnaeus, Des- 
fontaines, Decandolle, de Saussure, Bonnet, and 
Smith. 

The history of the peculiarities of structure in the 
different vegetable classes, rather belongs to botanical 
than agricultural knowledge. As I mentioned in the 
commencement of this Lecture, their organs are pos- 
sessed of the most distinct analogies, and are govern- 
ed by the same laws. In the grasses and palms, the 
cortical layers are larger in proportion than the other 
parts ; but their uses seem to be the same as in forest 
trees. 

In bulbous roots, the alburnous substance forms 
the largest part of the vegetable ; but in all cases it 
seems to contain the sap, or solid materials deposited 
from the sap. 

The slender and comparatively dry leaves of the 
pine and the cedar perform the same functions as the 
large and juicy leaves of the fig tree, or the walnut. 

K 



C 66 3 

Even in the cryptogamla, where no flowers are 
distinct, still there is every reason to believe that the 
production of the seed is eflfected in the same way as 
in the more perfect plants. The mosses and lichens, 
which belong to this family, have no distinct leaves, 
or roots, but they are furnished with filaments which 
perform the same functions ; and even in the fungus 
and the mushroom there is a system for the absorp- 
tion and aeration of the sap. 

It was stated in the last lecture, that all the differ- 
ent parts of plants are capable of being decomposed 
into a few elements. Their uses as food, or for the 
purposes of the arts, depend upon compound arrange- 
ments of those elements which are capable of being 
produced either from their organized parts, or from 
the juices they contain ; and the examination of the 
nature of these substances, is an essential part of Agri- 
cultural Chemistry. 

Oils are expressed from the fruits of many 
plants ; resinous fluids exude from the wood ; sac- 
charine matters are afforded by the sap ; and dyeing 
materials are furnished by leaves, or the petals of 
flowers : but particular processes are necessary to se- 
parate the different compound vegetable substances 
from each other, such as maceration, infusion or diges- 
tion in water, or in spirits of wine : but the application 
and the nature of these processes will be better under- 
stood when the chemical nature of the substances is 
known ; the consideration of them will therefore be 
reserved for another place in this Lecture. 



i: 67 ] 

The compound substances found in vegetables 
are, 1 gum, or mucilage, and its different modifica- 
tions ; 2, starch j 3, sugar ; 4, albumen ; 5, gluten ; 
6, gum elastic j 7, extract ; 8, tannin ; 9, indigo j 
10, narcotic principle ; 11, bitter principle ; 12, wax j 
13, resins ; 14, camphor ; 15, fixed oils ; 16, vola- 
tile oils J 17, woody fibre ; 18, acids ; 19, alkalies ; 
earths, metallic oxides, and saline compounds. 

I shall describe generally the properties and 
composition of these bodies, and the manner in which 
they are procured. 

1. Gum is a substance which exudes from certain 
trees ; it appears in the form of a thick fluid, but soon 
hardens in the air, and becomes solid : when it is 
white, or yellowish white, more or less transparent, 
and somewhat brittle j its specific gravity varies from 
1300 to 1490. 

There is a great variety of gums, but the best 
know are gum arabic, gum Senegal, gum tragacanth, 
and the gum of the plum or cherry tree. Gum is 
soluble in water, but not soluble in spirits of wine. If 
a solution of gum be made in water, and spirits of 
wine or alcohol be added to it, the gum separates in 
the form of white flakes. Gum can be made to in- 
flame only with difficulty ; much moisture is given off 
in the process, which takes place with a dark smoke 
and feeble blue flame, and a coal remains. 

The characteristic properties of gum are its easy 
solubility in water, and its insolubility in alcohol. Dif- 
ferent chemical substances have been proposed for 
ascertaining the presence of gum, but there is reason 



C 68 ] 

to believe that few of them afford accurate results ; and 
most of them (particularly the metallic salts,) which 
produce changes in solutions of gum, may be conceiv- 
ed to act rather upon some saline compounds existing 
in the gum, than upon the pure vegetable principle. 
Dr. Thomson has proposed an aqueous solution of 
silica in potassa as a test of the presence of gum in 
solutions — he states that the gum and silica are pre- 
cipitated together — this test, however, cannot be ap- 
plied with correct results in cases when acids are 
present. 

Mucilage must be considered as a variety of gum; 
it agrees with it in its most important properties, but 
seems to have less attraction for water. — According 
to Hermbstadt, when gum and mucilage are dissolved 
together in water, the mucilage may be separated by 
means of sulphuric acid — mucilage may be procured 
from Hnseed, from the bulbs of the hyacinth, from 
the leaves of the marsh-mallows ; from several of the 
lichens, and from many other vegetable substances. 

From the analysis of M. M. Gay Lussac and 
Thenard, it appears that gum arable contains in 100 
parts : 

of carbon - - - - 42,23 

— oxygene - - - - 50,84 

— hydrogene - - - 6,93 
with a small quantity of saline and earthy matter. 



or of carbon - - - 42,23 

oxygene and hydrogene in the pro- 1 
portions necessary to form water J 



C 69 ] 

This estimation agrees very nearly with the definite 
proportions of 11 of carbon, 10 of oxygene, and 20 
of hydrogene. 

All the varieties of gum and mucilage are nutri- 
tious as food. They either partially or wholly lose 
their solubility in water by being exposed to a heat 
of 500° or 600° Fahrenheit, but their nutritive powers 
are not destroyed unless they are decomposed. Gum 
and mucilage are employed in some of the arts, parti- 
cularly in calico-printing : till lately, in this country, 
the calico-printers used gum arabic ; but many of 
them, at the suggestion of Lord Dundonald, now 
employ the mucilage from lichens. 

2 Starch is procured from different vegetables, 
but particularly from wheat or from potatoes. To 
make starch from wheat, the grain is steeped in cold 
water till it becomes soft, and yields a milky juice by 
pressure ; it is then put into sacks of linen, and pres- 
sed in a vat filled with water : as long as any milky 
juice exudes the pressure is continued ; the fluid 
gradually becomes clear, and a white powder subsides, 
which is starch. 

Starch is soluble in boiling water, but not in 
cold water, nor in spirits of wine. According to 
Dr. Thomson, it is a characteristic property of starch 
to be soluble in a warm infusion of nutgalls, and to 
form a precipitate when the infusion cools. 

Starch is more readily combustible than gum ; 
when thrown upon red hot iron, it burns with a kind 
of explosion, and scarcely any residuum remains. 



C 70 ] 

According to Mr. Gay Lussac and Thenard, 100 

parts of starch are composed of 

Carbon, with a small quantity of 1 

saline and earthy matter - J ' "* 
Oxygene - - - . 49,68 

Hydrogene - - - - 6,77 



or. 



Carbon .... 43,55 

Oxygene and hydrogene in the"| 
proportions necessary to form r* 56,45 
water ^ - - - J 

Supposing this estimation correct, starch may be 
conceived to be constituted by 1 5 proportions of car- 
bon, 13 of oxygene, and 26 of hydrogene. 

Starch forms a principal part of a number of es- 
culent vegetable substances. Sowans, cassava, salop, 
sago, all of them owe their nutritive powers principal- 
ly to the starch they contain. 

Starch has been found in the following plants : 

Burdock ( Arctmn Lappa, J Deadly Nightshade 
(Jtropa Belladonna,) 'Bistort (Polygonum Bistort a, J 
White Bryony (Bryonia alba,) Meadow Saffron (Col^ 
chicum autumnale,J Drop wort (Spiraa Filipendula,) 
Buttercup (Ranunculus bulbosus,) Figwort ( Scrophu- 
laria nodosa,) Dwarf Elder (Sa?nbucus Ebulus,) Com- 
mon Elder (Sajnbucus nigra,) Foolstones (Orchis Mo- 
rio,J Alexanders (Imperatoria Ostruthium,) Henbane 
(Hyoscyajnus niger,) Broad-leaved Dock ( Rwnex obtu- 
sifolius,) Sharp Pointed Dock (Rumex acutus,) Water 
Dock {Rumex acquaticus,) Wake Robin {Arum Jiiacu- 



C 71 2 

latum,) Salep (Orchis mascida,) Flower de luce, or 
Water Flag {Iris Pseudacorus,) Stinking Gladwyn (^Iris 
fcctidissima,') Earthnut (Bunium Biilbocastanu?n.) 

3. Sugar in its purest state is prepared from the 
expressed juice of the Saccharu?n Officinarum, or sugar 
cane ; the acid in this juice is neutralized by lime, 
and the sugar is crystallized by the evaporation of the 
aqueous parts of the juice, and slow-cooling : it is 
rendered white by the gradual filtration of water 
through it. In the common process of manufacture, 
the whitening or refining of sugar is only affected in a 
great length of time ; the water being gradually suf- 
fered to percolate through a stratum of clay above the 
sugar. As the colouring matter of sugar is soluble 
in a saturated solution of sugar, or syrup, it appears 
that refining may be much more rapidly and oecono- 
mically performed by the action of syrup on coloured 
sugar.* The sensible properties of sugar are well 
known. Its specific gravity according to Fahrenheit 
is about 1.6. It is soluble in its own weight of water 
at 50° ; it is likewise soluble in alcohol, but in smal- 
ler proportions. 



• A French gentleman lately in this co*ntry (England), stated to the West 
India planters, that he was in possession of a very expeditious and economical 
method of purifying and refining sugar, which he was willing to communicate to 
them for a very great pecuniary compensation. His terms were too high to be 
acceded to. Conversing on the subject with Sir Joseph Banks, I mentioned to 
him, that I thought it probable that raw sugar might be easily purified by passing 
syrup through it, which would dissolve the colouring matKr. The same idea 
seems to have occurred about the same time, or before, to Edward Howard, Esq, 
who has since proved its efficacy experimentally, and has published an account of 
his process. 



C 72 ] 

Lavoisier concluded from his experiments, that 
sugar consists in 100 parts of 
28 carbon, 

8 hydrogene, 
64 OX} gene. 
Dr. Thomson considers 100 parts of sugar as 
composed of 27,5 carbon, 

7,8 hydrogene, 
64,7 oxygene. 
According to the recent experiments of Gay 
Lussac and Thenard, sugar consists of 
42,47 of carbon, and 
57,53 of water, or its elements. 
Lavoisier's and Dr. Thomson's analyses agree 
very nearly with the proportions of 

3 of carbon, 

4 of oxygene, and 
8 of hydrogene. 

Gay Lussac's and Thenard's estimation gives the 
same elements as in gum ; 11 of carbon, iO of oxy- 
gene, 20 of hydrogene. 

It appears from the experiments of Proust, Ach- 
ard, Goettling and Parmentier, that there are many- 
different species of sugar ready formed in the vegeta- 
ble kingdom. The sugar which most nearly resem- 
bles that of the cane is extracted from the sap of the 
American maple, Acer saccharinum. This sugar is used 
by the North American farmers, who procure it by a 
kind of domestic manufacture The trunk of the tree 
is bored early in spring, to the depth of about two in- 
ches ; a wooden spout is introduced into the hole j the 



C 73 3 

juice flows for about five or six weeks. A common 
sized tree, that is, a tree from two to three feet in 
diameter, will yield about 200 pints of sap, and every 
40 pints of sap afford about a pound of sugar. The 
sap is neutralized by lime, and deposits crystals of 
sugar by evaporation. 

The sugar of grapes has been lately employed in 
France as a substitute for colonial sugar. It is pro- 
cured from the juice of ripe grapes by evaporation, and 
the action of pot-ashes ; it is less sweet than common 
sugar, and its taste is peculiar : it produces a sensa- 
tion of cold while dissolving in the mouth ; and it is 
probable contains a larger proportion of water or its 
elements. 

The roots of the beet (^Beta vulgaris and cicla,^ 
afford a peculiar sugar, by boiling, and the evapora- 
tion of the extract : it agrees in its general properties 
with the sugar of grapes, but has a slightly bitter 
taste. 

Manna^ a substance which exudes from various 
trees, particularly from the Fraxinus Ornus, a species 
of ash, which grows abundantly in Sicily and Calabria, 
may be regarded as a variety of sugar, very analo- 
gous to the sugar of grapes. A substance analogous 
to manna has been extracted by Fourcroy and Vau- 
quelin, from the juice of the common onion (^Allium 
Cepa,) 

Besides the crystallized and solid sugars, there 
appears to be a sugar which cannot be separated from 
water, and which exists only in a fluid form ; it con- 
stitutes a principal part of melasses or treacle j and it 



is found in a variety of fruits : it is more soluble in 
alcohol than solid sugar. 

The simplest mode of detecting sugar is that re- 
commended by Margraaf. The vegetable is to be 
boiled in a small quantity of alcohol ; solid sugar, if 
any exist, will separate during the cooling of the solu- 
tion. 

Sugar has been extracted from the following ve- 
getable substances. 

The sap of the Bit ch (Betula alba,) of the Sy- 
camore (^Acer Pseudoplatanus,) of the Bamboo (^Arw> 
do Bambos,) of the Maize (Zea ?nays,') of the Cow 
Parsnip (Heracleum Sphondyliian,) of the Cocoa-nut 
tree {Cocos nucifera^ of the Walnut tree {Juglans 
alba,') of the American Aloe {^Agave mericana,') of the 
Dulse {Fiicus Palmaiiis,) of the Common Parsnip 
(JPastinica sativa,) of St. John's bread (Ceratonia Siii' 
qua,) the fruit of the common Arbutus {Arbutus 
Unedo,) and other sweet-tasted fruits ; the roots of 
the turnip (^Brassica Rapa,) of the carrot (^Daucus Car- 
Ota,) of Parsley (Apiwn Petrosel'mum,) the flower of 
the Euxine Rhododendron (^Rhododendron poniiciim,) 
and from the nectarium of most other flowers. 

The nutritive properties of sugar are well known. 
Since the British market has been over-stocked with 
this article from the West India, islands, proposals 
have been made for applying it as the food of cattle ; 
experiments have been made which proved that they 
may be fattened by it j but difficulties connected with 
the duties laid on sugar, have hitherto prevented th€ 
plan from being tried to any extent. 



4. Albumen Is a substance which has only lately 
been discovered in the vegetable kingdom. It abounds 
in the juice of the papavi'-tree (Carica papaya) : when 
this juice is boiled the albumen falls down in a coagu- 
lated state. It is likewise found in mushrooms, and 
in different species of funguses. 

Albumen in its pure form, is a thick, glairy, taste- 
less fluid ; precisely the same as the white of the Qgg ; it 
is soluble in cold water ; its solution, when not too di- 
luted, is coagulated by boiling, and the albumen separ- 
ates in the form of thin flakes. Albumen is likewise 
coagulated by acids and by alcohol : a solution of aU 
bumen gives a precipitate when mixed with a cold 
solution of nut-galls. Albumen when burnt produces 
a smell of volatile alkali, and affords carbonic acid and 
water ; it is therefore evidently principally composed 
of carbon, hydrogene, oxygene, and azote. 

According to the experiments of Gay Lussac and 
Thenard, 100 parts of albumen from the white of the 
egg are composed of 

Carbon - - 52,883 

Oxygene - - 2^,872 

Hydrogene - - 7,540 

Azote - - - 15,705 

This estimation would authorise the supposition, 
that albumen is composed of 2 proportions of azote, 
5 oxygene, 9 carbon, 22 hydrogene. 

The principal part of the almond, and of the 
kernels of many other nuts, appears from the experi- 
ments of Proust, to be a substance ana,logou5 to co- 
agulated albumen. 



C 76 ] 

The juice of the fruit of the Ochra (Hibiscus 
esciikntus), according to Dr. Clarke, contains a liquid 
albumen in such quantities, that it is employed in 
Dominica as a substitute for the white of eggs in clari- 
fying the juice of the sugar cane. 

Albumen may be distinguished from other sub- 
stances by its property of coagulating by the action of 
heat or acids, when dissolved in water. According 
to Dr- Bostock, when the solution contains only one 
grain of albumen to 1000 grains of water, it becomes 
cloudy by being heated. 

Albumen is a substance common to the animal 
as well as to the vegetable kingdom, and much more 
abundant in the former. 

5. Gluten may be obtained from wheaten flour by 
the following process : the flour is to be made into a 
paste, which is to be cautiously washed, by kneading 
it under a small stream of water, till the water has 
carried oflF from it all the starch ; what remains is 
gluten. It is a tenacious, ductile, elastic substance. 
It has no taste. By exposure to air it becomes of 
a brown colour. It is very slightly soluble in cold 
water but not soluble in alcohol. When a solution 
of it in water is heated, the gluten separates in the 
form of yellow flakes ; in this respect it agrees with 
albumen, but diflfers from it in being infinitely less 
soluble in water. The solution of albumen does not 
coagulate when it contains much less than 1000 parts 
of albumen ; but it appears that gluten requires more 
than 1000 parts of cold water for its solution. 



C 77 ] 

Gluten when burnt affords similar products to 
albumen, and probably differs very little from it in 
composition. Gluten is found in a great number of 
plants ; Proust discovered it in acorns, chesnuts, 
horse chesnuts, apples, and quinces ; barley, rye, peas 
and beans j likewise in the leaves of rue, cabbage, 
cresses, hemlock, borage, saffron, in the berries of 
the elder, and in the grape. Gluten appears to be 
one of the most nutritive of the vegetable substances ; 
and wheat seems to owe its superiority to other grain, 
from the circumstance of its containing it in larger 
quantities. 

6. Gu?n elastic, or Caoutchouc, is procured from 
the juice of a tree which grows in the Brazils, called 
Haevea. When the tree is punctured, a milky juice 
exudes from it, which gradually deposits a solid sub- 
stance, and this is gum elastic. 

Gum elastic is pliable and soft like leather, and be- 
comes softer when heated. In its pure state it is white ; 
its specific gravity is 9335. It is combustible, and 
burns with a white flame, throwing off a dense smoke, 
with a very disagreeable smell. It is insoluble in wa- 
ter, and in alcohol j it is soluble in ether, volatile oils, 
and in petroleum, and may be procured from ether in 
an unaltered state, by evaporating its solution in that 
liquid. Gum elastic seems to exist in a great variety 
of plants : amongst them are, Jatropha elastica, Ficus 
indica, Artocarpus integrifolia, and Urceola elastica. 

Bird-lime, a substance which may be procured 
from the holly, is very analogous to gum elastic in its 
properties. Species of gum elastic may be obtained 



from the misletoe, from gummastic, opium, and from 
the berries of the Smilax cadiica, in which last plant it 
has been lately discovered by Dr. Barton. 

Gum elastic, when distilled, affords volatile al- 
kali, water hydrogene, and carbon in different com- 
binations. It therefore consists principally of azote, 
hydrogene, oxygene, and carbon ; but the proportions 
in which they are combined have not yet been ascer» 
tained. Gum elastic is an indigestible substance, not 
fitted for the food of animals ; its uses in the arts are 
well known. 

7. Extract, or the extractive principle, exists in 
almost all plants. It may be procured in a state of 
tolerable purity from saffron, by merely infusing it in 
water, and evaporating the solution. It may likewise be 
obtained from catechu, or Terra japonica, a substance 
brought from India. This substance consists princi- 
pally of astringent matter, and extract ; by the action 
of water upon it, the astringent matter is first dissol- 
ved, and may be separated from the extract. Extract 
is always more or less coloured ; it is soluble in alcohol 
and water, but not soluble in ether. It unites with alu- 
mina when that earth is boiled in a solution of ex- 
tract , and it is precipitated by the salts of alumina, 
and by many metallic solutions, particularly the solu- 
tion of muriate of tin. 

From the products of its distillation, it seems to 
be composed principally of hydrogene, oxygene, car- 
bon, and a little azote. 

There appears to be almost as many varieties of 
extract as there are species of plants. The difference 



C V9 ] 

of their properties probably in many cases depends 
upon their being combined with small quantities of 
other vegetable principles, or to their containing differ- 
ent saline, alkaline, acid, or earthy ingredients. Many 
dyeing substances seem to be of the nature of extrac- 
tive principle, such as the red colouring matter of 
madder, and the yellow dye, procured from weld. 

Extract has a strong attraction for the fibres of 
cotton or linen, and combines with these substances 
when they are boiled in a solution of it. The com- 
bination is made stronger by the intervention of mor- 
dants, which are earthy or metallic combinations that 
unite to the cloth, and enable the colouring matter to 
adhere more strongly to its fibres. 

Extract, in its pure form, cannot be used as an 
article of food, but it is probably nutritive when united 
to starch, mucilage, or sugar. 

8. Tannin, or the tanning principle, may be pro- 
cured by the action of a small quantity of cold water 
on bruised grape-seeds, or pounded gall-nut ; and by 
the evaporation of the solution to dryness. It appears 
as a yellow substance, possessed of a highly astrin- 
gent taste. It is difficult of combustion. It is very 
soluble both in water and alcohol, but insoluble in 
ether. When a solution of glue, or isinglass (^gelatine') 
is mixed with an aqueous solution of tannin, the two 
substances, i. e. the animal and vegetable matters fall 
down in combination, and form an insoluble precipi- 
tate. 

When tannin is distilled in close vessels, the prin- 
cipal products are charcoal, carbonic acid, and inflam- 



t 80 ] 

mable gasses, with a minute quantity of volatile alkali. 
Hence its elements seem the same as those of extract, 
but probably in different proportions. The charac- 
teristic property of tannin is its action upon solutions 
of isinglass or jelly ; this particularly distinguishes it 
from extract, with which it agrees in most other che- 
mical qualities. 

There are many varieties of tannin, which pro- 
bably owe the difference of their properties to com- 
binations with other principles, especially extract, 
from which it is not easy to free tannin. The purest 
species of tannin is that obtained from the seeds of the 
grape ; this forms a white precipitate, with solution 
of isinglass. The tannin from gall-nuts resembles it 
in its properties. That from sumach affords a yellow 
precipitate ; that from kino a rose coloured ; that 
from catechu a fawn coloured one. The colouring 
matter of Brazil wood, which M. Chevreul considers 
as a peculiar principle, and which he has called Hcma- 
tine, differs from other species of tannin, in affording 
a precipitate with gelatine, which is soluble in abun- 
dance of hot water. Its taste is much sweeter than 
that of the other varieties of tannin, and it may per- 
haps be regarded as a substance intermediate between 
tannin and extract. 

Tannin is not a nutritive suostance, but is of 
great importance in its application to the art of tanning. 
Skin consists almost entirely of jelly or gelatine, in an 
organized state, and is soluble by the long continued 
action of boiling water When skin is exposed to so- 
lutions containing tannin, it slowly combines with 



c 



81 



] 



that principle j its fibrous texture and coherence are 
preserved ; it is rendered perfectly insoluble in water, 
and is no longer liable to putrefaction : in short, it 
becomes a substance in chemical composition pre- 
cisely analogous to that furnished by the solution of 
jelly and the solution of tannin. 

In general, in this country, the bark of the oak 
is used for affording tannin in the manufacture of 
leather ; but the barks of some other trees, particu- 
larly the Spanish chesnut, have lately come into use. 
The following table will give a general idea of the re- 
lative value of different species of barks. It is founded 
on the result of experiments made by myself. 

Table of Numbers exhibiting the quantity of Tannin af- 
forded by 480lbs, of different Barks, which express 
nearly their relative values. 



Average of entire bark of middle sized Oak, cut in spring, 
——————— of Spanish Ghesnut, 

— — — i. of Leicester Willow, large size, 



— of i'^lr 



— — — — .— of Common Willow, large, 

————————— of Beech, ... 

—————— of Horse Chesnut, 

— of Sycamore, 



-— — — of Lombard/ Poplari* 

— — . .,.— — of Birch, 

— — — — of Hazel, 

of Black Thorn 



— of Coppice Oak, 

— — —, — . — — of Oak cut in autumn. 



—————— of Larch, cut in autumn, ~ 

White interior cortical layers of Oak Bark, 



lb. 
29 
21 
33 
13 
II 
15 
10 

9 
II 
15 

8 
14 
15 
33 
21 



I 



The quantity of the tanning principle in barks 
differs in different seasons j when the spripg has been 

M 



L «2 3 

cold the quantity is smallest. On an average, 4 or 
5lbs. of good oak bark arc required to form lib. of 
Isather. The inner cortical layers in all barks con- 
tain the largest quantity of tannin. Barks contain the 
greatest proportion of tannin at the time the buds be- 
gin to open — the smallest quantity in winter. 

The extractive or colouring matters found in 
barks, or in substances used in tanning, influence the 
quality of leather. Thus skin tanned with gall-nuts 
is much paler than skin tanned with oak bark, which 
contains a brown extractive matter. Leather made 
from catechu is of a reddish tint. It is probable that 
in the process of tanning, the matter of skin, and the 
tanning principle first enter into union, and that leather 
at the moment of its formation unites to the extractive 
matter. 

In general, skins in being converted into leather 
increase in weight about one third ;* and the opera- 
tion is most perfect when they are tanned slowly. 
When skins are introduced into very strong infusions 
of tannin, the exterior parts immediately combine with 
that principle, and defend the interior parts from the 
action of the solution : such leather is liable to crack 
and to decay by the action of water. 

The precipitates obtained from infusions contain- 
ing tannin by isinglass, when dried, contain at a medi- 
um rate about 40 per cent, of vegetable matter. It 
is easy to obtain the comparative value of different 
substances for the use of the tanner, by comparing 

» This estimation must be considered as applying to dry skin and dry leather. 



C S3 3 

quantities of precipitate afforded by infusions of given 
weights mixed with solutions of glue or isinglass. 

To make experiments of this kind, an ounce or 
480 grains of the vegetable substance in coarse pow- 
der, should be acted upon by half a pint of boiling 
water. The mixture should be frequently stirred, and 
suffered to stand 24 hours ; the fluid should then be 
passed through a fine linen cloth and mixed with an 
equal quantity of solution of gelatine, made by dissolv- 
ing glue, jelly, or isinglass in hot water, in the pro- 
portion of a drachm of glue or isinglass, or six table 
spoonfuls of jelly, to a pint of water. The precipitate 
should be collected by passing the mixture of the solu- 
tion and infusion through folds of blotting paper j and 
the paper exposed to the air till its contents are quite 
dry. If pieces of paper of equal weights are used, in 
cases in which different vegetable substances are em- 
ployed, the difference of the weights of the papers 
when dried, will indicate with tolerable accuracy, the 
quantities of tannin contained by the substances, and 
their relative value, for the purposes of manufacture. 
Four tenths of the increase of weight, in grains, must 
be taken, which will be in relation to the weights in 
the table. 

Besides the barks already mentioned, there are a 
number of others which contain the tanning principle. 
Few barks indeed are entire free from it. It is like- 
wise found in the wood and leaves of a number of 
trees and shrubs, and is one of the most generally dif« 
fused of the vegetable principles. 

A substance very similar to tannin has been 



t 84 3 

formed by Mr. Hatchett, by the action of heated dila- 
ted nitric acid on charcoal, and evaporation of the 
mixture to dryness. From 100 grains of charcoal 
Mr. Hatchett obtained 120 grains of artificial tannin, 
which, like natural tannin, possessed the property of 
rendering skin insoluble in water. 

Both natural and artificial tannin form com- 
pounds with the alkalies and the alkaline earths ; and 
these compounds are not decomposable by skin. The 
attempts that have been made to render oak bark 
more efficient as a tanning material by infusion in lime 
water, are consequently founded on erroneons princi- 
ples. Lime forms with tannin, a compound not so- 
luble in water. 

The acids unite to tannin, and produce com- 
pounds that are more or less soluble in water. It is 
probable that in some vegetable substances tannin 
exists, combined with alkaline or earthy matter ; and 
such substances will be rendered more efficacious for 
the use of the tanner, by the action of diluted acids. 

9. Indigo may be procured from woad {Isatis tine- 
Uria,) by digesting alcohol on it, and evaporating the 
solution. White crystalline grains are obtained, 
which gradually become blue by the action of the at- 
mosphere : these grains are the substance in question. 

The indigo of commerce is principally brought 
from America. It is procured from the Indigofera 
argeniea, or wild indigo, the Indigofera disperma, or 
Gautimala indigo, and the Indigofera tinctoria, or 
French indigo. It is prepared by fermenting the 
leaves of those trees in water. Indigo in its common 



C 85 ] 

form appears as a fine, deep blue powder. It is in- 
soluble in water, and but slightly soluble in alcohol : 
its true solvent is sulphuric acid : 8 parts of sulphu- 
ric acid dissolve 1 part of indigo ; and the solution 
diluted with water forms a very fine blue dye. 

Indigo, by its distillation, affords carbonic acid 
gas, water, charcoal, ammonia, and some oily and 
acid matter : the charcoal is in very large proportion. 
Pure indigo therefore most probably consists of car- 
bon, hydrogene, oxygene, and azote. 

Indigo owes its blue colour to combination with 
oxygene. For the uses of the dyers it is partly de- 
prived of oxygene, by digesting it with orpiment and 
lime water, when it becomes soluble in the lime water, 
and of a greenish colour. Cloths steeped in this so- 
lution combine with the indigo ; they are green when 
taken out of the liquor, but become blue by absorb- 
ing oxgene when exposed to air. 

Indigo is one of the most valuable and most ex- 
tensively used of the dyeing materials. 

10. The narcotic principle is found abundantly in 
cpiu?}i, which is obtained from the juice of the white 
poppy, (Papaver album). To procure the narcotic 
principle, water is digested upon opium : the solution 
obtained is evaporated till it becomes of the consistence 
of a syrup. By the addition of cold water to this 
syrup a precipitate is obtained. Alchohol is boiled on 
this precipitate; during the cooling of the alcohol 
crystals fall down. These crystals are to be again 
dissolved in alcohol, and again precipitated by cool- 
ing : and the process is to be repeated till their colour 
is white j they are crystals of narcotic principle. 



C S6 ] 

The narcotic principle has no taste nor smell. It 
is soluble in about 400 parts of boiling water ; it is 
insoluble in cold water : it is soluble in 24 parts of 
boiling alcohol, and in 100 parts of cold alcohol. It 
is very soluble in all acid menstrua. 

It has been shewn by De Rosne, that the action 
of opium on the animal economy depends on this 
principle. Many other substances besides the juice 
of the poppy, possess narcotic properties ; but they 
have not yet been examined with much attention. 
The Lactuca saliva^ or garden lettuce, and most of 
the other lactucas yield a milky juice, which when 
inspissated has the characters of opium, and probably 
contains the same narcotic principle. 

1 1 . The bitter -principle is very extensively diffus- 
ed in the vegetable kingdom ; it is found abundantly 
in the hop {liumilus lupilus^ in the common broom 
{Spartium scoparium,') in the chamomile (Jnibemis 
nobi/is,) and in quassia, aniara and excelsa. It is ob- 
tained from those substances by the action of water or 
alcohol, and evaporation. It is usually of pale yellow 
colour ; its taste is intensely bitter. It is very solu- 
ble, both in water and alcohol ; and has little or no 
action on alkaline, acid, saline or metallic solution. 

An artificial substance, similar to the bitter prin- 
ciple, has been obtained by digesting diluted nitric 
acid, on silk, indigo, and the wood of the white willow. 
This substance has the property of dyeing cloth of a 
bright yellow colour ; it differs from the natural bitter 
principle in its power of combining with the alkalies : 
in union with the fixed alkalies it constitutes crystal- 



[ 87 ] 

iized bodies, which have the property of detonating 
by heat or percussion. 

The natural bitter principle is of great impor- 
tance in the art of brewing ; it checks fermentation, 
and preserves fermented liquors ; it is likewise used 
in medicine. 

The bitter principle, like the narcotic principle, 
appears to consist principally of carbon, hydrogene, 
and oxygene, with a little azote. 

1 2. Wax is found in a number of vegetables ; it 
is procured in abundance from the berries of the wax 
myrtle (Myrica ceriferd)^ it may be likewise obtained 
from the leaves of many trees ; in its pure state it is 
white. Its specific gravity is 9,662 ; it melts at 155 
degrees ; it is dissolved by boiling alcohol ; but it is 
not acted upon by cold alcohol ; it is insoluble in wa- 
ter ; its properties as a combustible body are well 
known. 

The wax of the vegetable kingdom seems to be pre- 
cisely of the same nature as that afforded by the bee. 

From the experiments of M. M. Gay Lussac and 
Thenard, it appears that 100 parts of wax consist of 

Carbon - - - - 81,784^ 

Oxygene » , - - 5,544 

Hydrogene - - = = 12,672 
or otherwise, 

Carbon „ . - . 81,784 

Oxygene and hydrogene in the pro-*) 

. r r 6,300 

portions necessary to form water J 

Hydrogene - - - 11,916 

which agrees very nearly with 37 proportions of hv- 

drogene, 21 of charcoal, 1 of oxygene. 



I 88 ] 

13. Resin is very common in the vegetable king« 
dom. One of the most usual species is that afforded 
by the different kinds of fir. When a portion of the 
bark is removed from a fir tree in spring, a matter 
exudes, which is called turpentine ; by heating this 
turpentine gently, a volatile oil rises from it, and a 
more fixed substance remains j this substance is 
resin. 

The resin of the fir is the substance commonly 
known by the name of rosin ; its properties are well 
known. Its specific gravity is 1072. It melts readily, 
burns with a yellow light, throwing off much smoke. 
Resin is insoluble in water either hot or cold ; but 
very soluble in alcohol. When a solution of resin in 
alcohol is mixed with water, the solution becomes 
milky ; the resin is deposited by the stronger attrac- 
tion of the water for the alcohol. 

Resins are obtained from many other species of 
trees. Masticb, from the Pistacia lentiscusy Elejiii 
from the Amyris elemifera. Copal from the Rhus copaU 
Hnum, Sandarach from the common juniper. Of these 
resins copal is the most peculiar. It is the most diffi- 
cultly dissolved in alcohol ; and for this purpose 
must be exposed to that substance in vapour , or the 
alcohol employed must hold camphor in solution. Ac- 
cording to Gay Lussac and Thenard, 
100 parts of common resin contain 

Carbon - - . - 75,944 

Oxygene ... - 13,33? 

Hydrogene - - - - 10,719 



t 89 J 

or of 

Carbon - - - - 75,944 

Oxygene and hydrogene in the pro- 1 

portioiis necessary to form water J '^' "* 
Hydrogfflie in excess - - 8,900 

According to the same chemists, 100 parts of co- 
pal consist of 

Carbon . - . . 76,811 

Oxygene - - - . 10,606 

Hydrogene - - - - 12,583 
or, 

Carbon - - . . 76,811 

Water or its elements - - 12,052 
Hyrogene - - - - 11,137 
From these results, if resin be a definite com- 
pound, it may be supposed to consist of 8 proportions 
of carbon, 1 2 of hydrogene, and 1 of oxygene. 

Resins are used for a variety of purposes. Tar 
and pitch principally consist of resin, in a partially de- 
composed state. Tar is made by the slow combustion 
of the fir ; and pitch by the evaporation of the more 
volatile parts of tar. Resins are employed as var- 
nishes, and for these purposes are dissolved in alco- 
hol or oils. Copal forms one of the finest. It may 
be made by boiling it in powder with oil of rosemary, 
and then adding alcohol to the solution. 

14. Camphor is procured by distilling the wood 
of the camphor tree {Laurus Camphora^ which grows 
in Japan. It is a very volatile body, and may be pu- 
rified by distillation. Camphor is a white, brittle, 
semitransparent substance, having a peculiar odour, 

N 



[ 90 3 

and a strong acrid taste. It is very slightly soluble 
in water ; more than 1 00,000 parts of water are re- 
quired to dissolve 1 part of camphor. It is very solu- 
ble in alcohol ; and by adding water in small quantities 
at a time to the solution of camphor in alcohol, the 
camphor separates in a crystallised form. It is solu- 
ble in nitric acid, and is separated from it by water. 

Camphor is very inflammable ; it burns with a 
bright flame, and throws off a great quantity of car- 
bonaceous matter. It forms in combustion water, 
carbonic acid, and a peculiar acid called camphoric 
acid. No accurate analysis has been made of camphor, 
but it seems to approach to the resins in its composi- 
tion ; and consists of carbon, hydrogene, and oxy- 
gene 

Camphor exists in other plants besides the Lau- 
rus camphora. It is procured from species of the lau- 
rus growing in Sumatra, Borneo, and other of the 
East Indian isles. It has been obtained from thyme 
(Thymus serpillum^ marjorum {Origanum majorana^ 
Ginger tree {Amomum Zingiber.^ Sage {Salvia officiri' 
alts.') Many volatile oils yield camphor by being 
merely exposed to the air. 

An artificial substance very similar to camphor 
has been formed by M. Kind, by saturating oil of tur- 
pentine with muriatic acid gas (the gaseous substance 
procured from common salt by the action of sulphuric 
acid). The camphor procured in well conducted ex- 
periments amounts to half of the oil of turpentine 
used. It agrees with common camphor in most of its 
sensible properties j but differs materially in its che- 



[ 91 3 

mical qualities and composition. It is not soluble 
without decomposition in nitric acid. From the ex- 
periments of Gehlen, it appears to consist of the ele- 
ments of oil of turpentine, carbon, hydrogene and 
oxygene, united to the elements of muriatic gas, 

chlorine and hydrogene. 

From the analogy of artificial to natural camphor, 

it does not appear improbable, that natural camphor 
may be a secondary vegetable compound, consisting 
of camphoric acid and volatile oil. Camphor is used 
medicinally, but it has no other application. 

15. Fixed oil is obtained by expression from seeds 
and fruits ; the olive, the almond, linseed and rape- 
seed afford the most common vegetable fixed oils. 
The properties of fixed oils are well known. Their 
specific gravity is less than that of water ; that of ohve 
and of rape-seed oil is 913; that of linseed and al- 
mond oil 932 ; that of palm oil 968 ; that of walnut 
and beech mast oil 923. Many of the fixed oils con- 
geal at a lower temperature than that at which water 
freezes. They all require for their evaporation a 
higher temperature than that at which water boils. 
The products of the combustion of oil are water, and 
carbonic acid gas. 

From the experiments of Gay Lussac and Then= 
ard, it appears that olive oil contains, in 100 parts, 
Carbon - - - - 77,213 
Oxygene - - - - 9,427 

Hydrogene - - - . 13,360 
This estimation is a near approximation to 1 1 pro^ 
portions of carbon, 20 hydrogene, and 1 oxygene. 



C 9'^ J 

The following is a list of fixed oils, and of the 
trees that afford them. 

Olive oil, from the Olive tree (Olea Europea), 
Linseed oil, from the common and perennial Flax 
(Linum usitatissimian et perenne.^ Nut oil, from the 
Hazel nut (Coryllus avelland). Walnut (^Juglans regia). 
Hemp oil, from the Hemp (Cannabis sativa). Almond 
oil, from the sweet Almond (A?nygdalus communis^ 
Beech oil, from the common Beech (Fagus syhatica\ 
Rape-seed oil, from the Rapes (Brassica napus et cam- 
pestris). Poppy oil, from the Poppy (Papaver somnife' 
rwii)^ oil of Sesamum, from the Sesamum (Sesamum 
orientate)., Cucumber oil, from the Gourds (Cucurbita 
pepo et malapepd)^ oil of Mustard, {Sinapis nigra et ar- 
vensis), oil of Sunflower, from the annual and peren- 
nial Sunflower, (Heliantbiis an?iuus et peremiis\ Castor 
oil, from the Palma Christi (Ricinus co?nmums). To- 
bacco {Nicotiana tabaciim et rustica\ Plum kernel oil, 
from the Plum tree (Primus domestical. Grape-seed 
oil, from the Vine (Vitis vi?nfera'). Butter of cacoa, 
from the Cacoa tree (Tbeobro?na cacoa,) Laurel oil, 
from the sweet Bay tree (Lauriis nobilis). 

The fixed oils are very nutritive substances ; they 
are of great importance in their applications to the 
purposes of life. Fixed oil, in combination with soda, 
forms the finest kind of hard soap. The fixed oils 
are used extensively in the mechanical arts, and for 
the preparation of pigments and varnishes. 

16. Volatile oil, likewise called essential oil, differs 
from fixed oil, in being capable of evaporation by a 
much lower degree of heat ; in being soluble in alco- 



[ 93 ] 

hoi, and in possessirg a very slight degree of solubili- 
ty in water. 

There is a great number of volatile oils, distin- 
guished by their smell, their taste, their specific gra- 
vity, and other sensible qualities. A strong and pecu- 
liar odour may however be considered as the great 
characteristic of each species ; the volatile oils inflame 
with more facility than the fixed oils, and afford by 
their combustion different proportions of the same 
substances, water, carbonic acid, and carbon. 

The following specific gravities of different vola- 
tile oils were ascertained by Dr. Lewis. 

Oil of Sassafras 1094 Oil of Tansy 946 

■ Caraway 940 

Origanum 940 

■^ Spike 936 

Rosemary 934 

Juniper 911 

Oranges 88S 

Turpentine 792 



Cinnamon 


1035 


Cloves 


1034 


Fennel 


997 


Dill 


994 


Penny Royal 


978 


Cummin 


975 


Mint 


975 


Nutmegs 


948 



The peculiar odours of plants seem, in almost 
all cases, to depend upon the peculiar volatile oils they 
contain. All the perfumed distilled waters owe their 
peculiar properties to the volatile oils they hold in so- 
lution. By collecting the aromatic oils, the fragrance 
of flowers, so fugitive in the common course of na- 
ture, is as it were embodied and made permanent. 

It cannot be doubted that the volatile oils con- 
sist of carbon, hydrogene, and oxygene ; but no ac- 
curate experiments have as yet been made on the 
proportions in which these elements are combined. 



C 9* 3 

The volatile oils have never been used as articles 
of food ; many of them are employed in the arts, in 
the manufacture of pigments and varnish ; but their 
most extensive application is as perfumes. 

17 Woody fibre is procured from the wood, bark, 
leaves, or flowers of trees, by exposing them to the 
repeated action of boiling water and boiling alcohol. 
It is the insoluble matter that remains, and is the basis 
of the solid organized parts of plants. There are as 
many varieties of woody fibre as there are plants and 
organs of plants ; but they are all distinguished by 
their fibrous texture, and their insolubility. 

Woody fibre burns with a yellow flame, and pro- 
duces water and carbonic acid in burning When it 
is distilled in close vessels, it yields a considerable 
residuum of charcoal. It is from woody fibre, indeed, 
that charcoal is procured for the purposes of life 

The following table contains the results of expe- 
riments made by Mr. Mushet, on the quantity of char- 
coal afibrded by different wood. 
100 parts of Lignum Vitas - 26,8 of charcoal 

'• Mahogany - 25,4 

Laburnum - 24,5 

Chesnut - - 23,2 

Oak - - 22,6 



— American black Beech 2 1 ,4 

— Walnut - - 20,6 

— Holly - . 19,9 
-Beech - - 19,9 

— American Maple 1 9,9 
-Elm - - 19,5 



C 95 3 

100 parts of Norway Pine - 19,2 of charcoal 
Sallow - - 18,4 



•Ash ^ . 17,9 

Birch - - 17,4 
Scottish Fir - 16,4 



M, Gay Lussac and Thenard have concluded 
from their experiments on the wood of the oak and 
the beech, that 1 00 parts of the first contain : 

of Carbon - - - - 52,53 

— Oxygene - . - 41, 7S 

— Hydrogene .. - - 5,69 
and 100 parts of the second : 

of Carbon - - - - 51,45 

— Oxygene - - - 42,73 

— Hydrogene - - - 5,82 
Supposing woody fibre to be a definite compound, 

these estimations lead to the conclulfen, that it con- 
sists of 5 proportions of carbon, 3 of oxygene, and 
6 of hydrogene ; or 57 carbon, 45 oxygene, and 6 
hydrogene. 

It will be unnecessary to speak of the applications 
of woody fibre. The different uses of the woods, 
cotton, linen, the barks of trees, are sufficiently 
known. Woody fibre appears to be an indigestible 
substance. 

18. The acids found in the vegetable kingdom 
are numerous ; the true vegetable acids which exist 
ready formed in the juices or organs of plants, are 
the oxalic, citric^ tartaric, benzoic, acetic, malic, gallic, 
and prussic acid. 



C 96 ] 

All these acids, except the acetic, malic, and 
prussic acids, are white crystallized bodies. The 
acetic, malic, and prussic acids have been obtained in 
the only fluid state ; they are all more or less solu- 
ble in water ; all have a sour taste except the gallic 
and prussic acids ; of which the first has an astringent 
taste, and the latter a taste like that of bitter almonds. 

The oxalic acid exists, uncombined, in the liquor 
T^hich exudes from the Chich pea (Cicer ariet'muni)^ 
and may be procured from wood sorrel (Oxalis aceto- 
5ella\ common sorrel, and other species of Rumex ; 
and from the Geranium acidum. Oxalic acid is easily 
discoved and distinguished from other acids by its 
property of decomposing all calcareous salts, and 
forming with lime a salt insoluble in water ; and by 
its crystallizing in four-sided prisms. 

The citric.acid is the peculiar acid existing in the 
juice of lemons and oranges. It may likewise be ob- 
tained from the cranberry, whortleberry, and hip. 

Citric acid is distinguished by its forming a salt 
insoluble in water with lime ; but decomposable by 
the mineral acids. 

The tartaric acid may be obtained from the juice 
•of mulberries and grapes ; and likewise from the pulp 
of the tamarind. It is characterized by its property 
of forming a difficultly soluble salt with potassa, and 
an insoluble salt decomposable by the mineral acids 
with lime. 

Benzoic acid may be procured from several re- 
sinous substances by distillation ; from benzoin, 
storax, and balsam of Tolu. It is distinguished from 



C 97 ] 

the other acids by its aromatic odour, and by its ex- 
treme volatility. 

Malic acid may be obtained from the juice of 
apples, barberries, plums, elderberries, currants, 
sta wherries, and raspberries. It forms a soluble salt 
with lime ; and is easily distinguished by this test 
from the acids already named. 

Acetic acid, or vinegar, may be obtained from 
the sap of different trees. It is distinguished from 
malic acid by its peculiar odour ; and from the other 
vegetable acids by forming soluble salts with the alka- 
lies and earths. 

Gallic acid may be obtained by gently and gradu- 
ally heating powdered gall nuts, and receiving the vo- 
latile matter in a cool vessel. A number of white 
crystals will appear, which are distinguished by their 
property of rendering solutions of iron, deep purple. 

The vegetable prussic acid is procured by distil- 
ling laurel leaves, or the kernels, of the peach, and 
cherry, or bitter almonds, li is characterized by its 
property of forming a blueish green precipitate, when 
a little alkali is added to it, and it is poured into solu- 
tions containing iron. It is very analogous in its pro- 
perties to the prussic acid obtained from animal sub- 
stances ; or by passing ammonia over heated charcoal ; 
but this last body forms, with the red oxide of iron, 
the deep bright blue substance, called Prussian blue. 

Two other vegetable acids have been found in 
the products of plants ; the morolyxic acid in a saline 
exudation from the white mulberry tree, and the kinic- 
acid in a salt afforded by Peruvian bark j but these 

o 



C ^8 J 

two bodies have as yet been discovered in no other 
cases. The phosphoric acid is found free in the 
onion ; and the phosphoric, sulphuric, muriatic, and 
nitric acids, exist in many saline compounds in the 
vegetable kingdom ; but they cannot with propriety 
be considered as vegetable products. Other acids 
are produced during the combustion of vegetable 
compounds, or by the action of nitric acid upon 
them ; they are the camphoric acid, the mucous or 
saclactic acid, and the suberic acid ; the first of which 
is procured from camphor ; the second from gum or 
mucilage ; and the third from cork, by the action of 
nitric acid. 

From the experiments that have been made upon 
the vegetable acids, it appears that all of them, except 
the prussic acid, are constituted by different propor- 
tions of carbon, hydrogene, and oxygene ; the prus- 
sic acid consists of carbon, azote and hydrogene, with 
a little oxygene. The gallic acid contains more car- 
bon than any of the other vegetable acids. 

The following estimates of the composition of 
some of the vegetable acids have been made by Gay 
Lussac and Thenard. 
100 parts of oxalic acid contain : 

Carbon - - . . 26,566 

Hydrogene - - - - 2,745 

Oxygene - - - - 70,689 
Ditto of tartaric acid : 

Carbon - . - - 24,050 

Hydrogene - - - - 6,629 

Oxygene - - » - 69,32! 



I 99 J 

100 parts of citric acid : 

Carbon - - , - 33,811 

Hydrogene - - - _ 6,330 

Oxygene - - „ _ 59,859 
Ditto acetic acid : 

Carbon - » » , 50,224 

Hydrogene , - > 5,620 

Oxygene . - - - 44,147 
Ditto mucous or saclactic acid ; 

Carbon - . - _ 33,69 

Hydrogene - - - 3,62 

Oxygene - - . . 62,69 

These estimations agree nearly with the follow- 
ing definite proportions. In oxalic acid 7 proportions 
of carbon, 8 of hydrogene, and 15 oxygene;* in tar- 
taric acid, 8 carbon, 28 hydrogene, 18 oxygene; in 
citric acid, 3 carbon, 6 hydrogene, 4 oxygene ; in 
acetic acid, 18 carbon, 22 hydrogene, 12 oxygene; 
in mucous acid, 6 carbon, 7 hydrogene, 8 oygene. 

The applications of the vegetable acids are well 
known. The acetic and citric acids are extensively 
used. The agreeable taste and wholesomeness of 
various vegetable substances used as food, materially 
depend upon the vegetable acid they contain. 

19. Fixed Alkali may be obtained In aqueous so- 
lution from most plants by burning them, and treat- 
ing the ashes with quick lime and water. The vege- 



* According to Dr. Thompson's experiments, oxalic acid consists of 3 pro- 
portions of carbon, 4 of oxygene, and 4 of hydrogene, a result very different indeed 
from that of the French chemists. 



^ 



[ 100 ] 

table alkali, or potassa, is the common alkali, or pot- 
assa, is the common alkali in the vegetable kingdom. 
This substance in its pure state is white, and semi- 
transparent, requiring a strong heat for its fusion, and 
possessed of a highly caustic taste. In the matter 
usually. called pure potassa by chemists, it exists com- 
bined with water ; and in that commonly called pearl 
ashes, or pot-ashes in commerce, it is combined with 
a small quantity of carbonic acid. Potassa in its com- 
bined state, as has been mentioned, page 47, consists 
of the highly inflammable metal potassium, and oxy- 
gene, one proportion of each. 

Soda, or the mineral alkali, is found in some 
plants that grow near the sea ; and is obtained com- 
bined with water, or carbonic acid, in the same man- 
ner as potassa j and consists, as has been stated, 
page 47, of one proportion of sodium, and two pro- 
portions of oxygene. In its properties it is very simi- 
lar to potassa ; but may be easily distinguished from it 
by this character ; it forms a hard soap with oil ; 
potassa forms a soft soap. 

Pearl ashes, and barilla and kelp, or the impure 
soda obtained from the ashes of marine plants, are 
very valuable in commerce, principally on account of 
their uses in the manufacture of glass and soap. Glass 
is made from fixed alkali, flint, and certain metallic 
substances. 

To know whether a vegetable yields alkali, it 
should be burnt, and the ashes washed with a small 
quantity of water. If the water, after being for some 
time exposed to the air, reddens paper tinged with 



C 101 3 

turmeric ; or renders vegetable blues, green, it con- 
tains alkali. 

To ascertain the relative quantities of pot-ashes 
afforded by different plants, equal weights of them 
should be burnt : the ashes washed in twice theii 
volume of water ; the washings should be passed 
through blotting paper, and evaporated to dryness : 
the relative weights of the salt obtained, will indicate 
very nearly the relative quantities of alkali they con- 
tain. 

The value of marine plants in producing soda, 
may be estimated in the same manner, with sufficient 
correctness for all commercial purposes. 

Herbs, in general, furnish four or five times, and 
shrubs two or three times as much pot-ashes as trees. 
The leaves produce more than the branches, and the 
branches more than the trunk. Vegetables burnt in 
a green state produce more ashes than in a dry state. 

The following table* contains a statement of the 
quantity of pot-ashes afforded by some common trees 
and plants. ^* -l^/l,^ 

10,000 parts of Oak - ^"^It-'-^^^^^S-^^-^ 

of Elm - - 39 

X)f Beech - - 12 

' ■ of Vine - - 55 

of Poplar - - 7 

of Thistle - 53 

•— — of Fern - - 62 

of Cow Thistle - 1 96 

• It is founded upon the experiments of Kirwan, Vauquelln and Pertuts. 



[ 102 3 

10,000 parts of Wormwood - 730 

. of Vetches - 275 

— of Beans - - 200 

of Fumitory - 790 

The earths found in plants are four : silica or 
the earth of flints, alumina or pure clay, lime and 
magnesia. They are procured by incineration. The 
lime is usually combined with carbonic acid. This 
substance and silica are much more common in the 
vegetable kingdom than magnesia, and magnesia more 
common than alumina. The earths form a principal 
part of the matter insoluble in water, afforded by the 
ashes of plants. The silica is known by not being 
dissolved by acids ; the calcareous earth, unless the 
ashes have been very intensely ignited, dissolves with 
effervescence in muriatic acid. Magnesia forms a solu- 
ble and crystallizable salt, and lime, a difficultly solu- 
ble one with sulphuric acid. Alumina is distinguished 
from the other earths, by being acted upon very slowly 
by acids ; and in forming salts very soluble in water, 
and difficult of crystallization with them. 

The earths appear to be compounds of the pecu- 
liar metals mentioned page 48 and oxygene, one pro- 
portion of each. 

The earths afforded by plants are applied to no 
uses of common life ; and there are few cases in 
which the knowledge of their nature can be of impor- 
tance, or aiford interest to the farmer. 

The only vietaUic oxides found in plants, are those 
of iron and manganesum : they are detected in the 



C 103 1 

ashes of plants ; but in very minute quantities only. 
When the ashes of plants are reddish brown, they 
abound in oxides of iron. When black or purple, in 
oxide of manganesum ; when these colours are mixed 
they contain both substances. 

The saline compounds contained in plants, or 
afforded by their incineration, are very various. The 
sulphuric acid combined with potassa, or sulphate of 
potassa, is one of the most usual. Common salt is 
likewise very often found in the ashes of plants ; like- 
wise phosphate of lime, which is insoluble in water, 
but soluble in muriatic acid. Compounds of the nitric, 
muriatic, sulphuric, and phosphoric acids, with alkalies 
and earths, exist in the sap of many plants, or are af- 
forded by their evaporation and incineration. The 
salts of potassa are distinguished from those of soda, 
by their producing a precipitate in solutions of pla- 
tina : those of lime are characterized by the cloudiness 
they occasion in solutions containing oxalic acid j 
those of magnesia, by being rendered cloudy by solu- 
tions of ammonia. Sulphuric acid is detected in salts 
by the dense white precipitate it forms in solutions of 
baryta. Muriatic acid by the cloudiness it communi- 
cates to solution of nitrat of silver ; and when salts 
contain nitric acid, they produce scintillations by being 
thrown upon burning coals. 

As no applications have been made of any of the 
neutral salts, or analogous compounds found in plantSj 
in a separate state, it will be useless to describe them 
individually. The following tables are given from 



c 



104 



3 



M. Th. de Satissure's Researches on Vegetation, and 
contain results obtained by that philosopher. They 
exhibit the quantities of soluble salts, metallic oxides, 
and earths afforded by the ashes of different plants. 







1 Constituents 


of 100 parts 1 


_ 




; of the Ashes. [ 


Names of Plants, 
f 
1 
1 
1 

1 


Cm 





1 












a. u 

u 

-• c 

1..- 


1 Water from 1000 parts 
the Plant green 


1 
1, 

1 ^ 
1 " 
i ii 

1 1 

en 

47 ~ 


a 

.c 
a, 


24 


c 


J3 

u 
a 
U 

k. 

n 
U 

0,12 


in 
3 




IS 


1 




\ Leaves of oak (quercus rabur) May 10 


13 j i 


31 745 


0,64 25,54 1 


2 Ditto, Sept. 27 - - - 


24 1 i 


5 549 


17 


18,25 


23 


14,5 


1,75 25,5 


3 Wood of a young oak, May 10 


— 


4 


26 


28,5 I12.25 


0,12 


J 32,58 


4 Bark of ditto 


— e 


— 


7 


4,5 


63,25 


0,25 


1,75 22,75 


5 Entire wood of oak 


— 


2 


38,6 


4,5 


33 


2 


2,25 20,65 


6 Alburnum of ditto - 


— 





32 


24 


11 


7,5 


2 23,5 


7 Bark of ditto . . - . 


— 6 





7 


3 


66 


1,5 


2 21,5 


8 Cortical layers of ditto - 


— 7 


3 — 


7 


3,75 


65 


0,5 


1 22,75 


9 Extract of wood of ditto - 


— 6 




51 










10 Soil from wood of ditto - 


— 4 


I 


24 


10,5 


10 


32 


14 8,5 


11 Extract from ditto - 


- 11 


1 


66 










12 Leaves of the poplar (populus nigra) 


— 














May 26 .... 


23 6 


6 652 


35 


13 


29 


5 


1,25 15,75 


13 Ditto Sept. 1-2 ... 


41 j9 


3 565 


3i 


7 


3e 


11,5 


1,5 18 


■14 Wood of ditto. Sept, 12 


— 1 


8 26 


— 


16,75 


27 


3,3 


1,5 24,5 


IS Bark of ditto .... 


- 17 


2 


6 


5,3 


60 


4 


1,5 23,2 , 


;i6 Leaves of hazel {corylus avellatia) 
















\ May 1 .... 


— 6 


1 


26 


23,3 


22 


2,5 


1,5 24,7 


'l7 Ditto, washed in cold water 


— , 5 


7 1 


8,2 


19,5 


44,1 


4 


2 ;22,2 


|l8'Leaves of ditto June 22 - 


23 1 6 


2 655 j 


22,7 


M 


29 


11,3 


1,5 121,5 


19 Ditto Sept. 20 - 


31 ' 7 


557! 


11 


12 


36 


22 


2 ' 17 


10 Wood of ditto. May 1 


— 


5 ' 


24,5 35 


8 


0,25 


0,12 32,2 


'31 Bark of ditto .... 


- 6 


2 


12,5 5,5 


54 


0,25 


1,75 26 


122 Entire wood of mulberry (morui ni- 












1 1 


j Sra), November . 


— 


7 


21 


2,25 


56 


0,12 


0,25 1 20,38 


23 Alburnum of ditto ... 


- 1 


3 1 


26 27,25 


24 


1 


0,25 21,5 


■24 Bark of ditto 


— 8 


•) ! 


7 


8,5 


45 


15,25 


1,12,23,13 


25 Cortical layers of ditto - 


~ 8 


8 


10 


16,5 


48 


0,12 


1 24,38 


■26 Entire wood of hornbeam (carpinui 
















j betuluO, Nov. 


4 


6 346 


22 


23 


26 


0,12 


3,25 26,63 


27 Alburnum of ditto - 


4 


7 390 


18 


36 


15 


1 


1 29 


'28; Bark of ditto 


88 13 


4 346 


4,5 


4,5 


59 


1,5 


0,12 30,38 


fag Wood of horse chesnut (sscttlus hyp- 


















1 pocastanum) May 10 


— 3 


5 


9,5 












,30 Leaves of ditto. May 10 - 


16 7 


2 782 


50 












|31 Leaves of ditto, July 23 . 


29 8 


1 652 


24 












h2 Ditto, Sept. 27 


31 8 


i 630 


13,5 












ha Flowers of ditto. May 10 


9 7 


1 873 


50 













105 



1 


Constituents of 100 parts 




of the Ashes. 


in 

C 

O 

CO 

o 

2 


"3 

li 

o i 

" c 

< 


o 

5 


o 

is 

o ^ 

o ao 

S " 

c 
^ a 
35; 

1 


in 

3 
3 
"3 


.a 


1:4 
« 


1 
a 


JO 
u 

U 

;►> 

S 


rt 


. i 

'Z 


M 

2 




i 


34 Fruit of horse chesnut {Sicuhii hyp- 














: j 


pocastanum) Oct. 5 - - 


12 


34 


647 


82 


12 





0,5 


0,25 j 5,25 


35 Plants of peas (p«j«m sativuin)ia &o'r 


— 


95 





49,80 


17,25 


6 


2,3 


1 24,65 


36 Ditto, ripe .... 


— 


81 





34,25 


22 


14 


II 


2,5 


17,25 


37 Plants of vetches (-uic/a /uJ«), be- 


















fore flowering. May 23 


16 


150 


895 


55.5 


14,5 


3,5 


1.5 


0,5 


24,50 


38 Ditto in flower, June 23 - 


20 


122 


876- 


55,5 


13,5 


4.12 


1,5 


0,5 


24,38 


39 Ditto ripe, June 23 - 


— 


66 





50 


17,75 


4 


1,75 


0,5 


26 


40 Ditto, seeds separated 


— 


115 





42 


5,75 


3§ 


1,75 


1 


12,9 


41 Seeds of ditto 


— 


33 





69,23 


27.92 








0,5 


2,3 


4i Do. ill flower, rais'd in distilled water 


— 


39 





60,1 


30 








0,5 


9,4 


43 Solydago vulgaris, before flowering, 




















May 1 .... 


— 


92 





67,5 


10,75 


1.5 


1,5 


0,75 


18,25 


44 Ditto, just in flower, July 15 - 


— 


57 





59 . 


59 


1,5 


1,5 


0,75 


21 


15 Ditto, seeds ripe, Sep. 20 


— 1 


50 





43 


11 


17,25 


3,5 


1,5 


18,75 


46 Plants of turnsol (helianthui annuus), 




















a month before flowering, June 23 


— 


147 





63 


67 


11,56 


1,5 


0,12 


16,67 


47 Ditto in flower, July 23 - 


13 


137 


877 


61 


6 


12,5 


1,5 


0,12 


18,78 


48 Ditto, bearing ripe seeds, Sept. 20^ 


23 


93 


753 


5,15 


22,5 


4 


3,75 


0,5. 


17,75 


49 Wheat (triticum sativum), in flower 


— 


— 





43,35 


12,75 


0,25 


32 


0,5 


12,25 


50 Ditto, seeds ripe ... 


— 


— 





11 


15 


0,25 


54 


1 


18,75 


51 Ditto, a month before flowering 


— 


79 





60 


11,5 


0,25 


12,5 


0,25 


15.5 


52 Ditto, in flower, June 14 - 


16 


54 


699 


41 


10,75 


0,25 


26 


0,5 


21.5 


53 Ditto, seeds ripe ... 


— 


33 





10 


11,75 


0,25 


51 


0,57 


23 


54 Straw of wheat 


— 


43 





22,5 


6,2 


1 


61.5 


1 


78 


55 Seeds of ditto 


— 


13 





47,16 


44,5 





0,5 


0,25 


7.6 


56 Bran 


— 


52 




4,16 


46>5 





O.S 


0,25 


8.6 


57 Plants of maize (zea mays) a month 




















before flowering, June 23 


— 


122 




69 


5,75 


0,25 


7,5 


0,25 


17,25 


58 Ditto, in flower, July 23 


— 


81 




69 


6 


0.25 


7,5 


0,25 


17 


5^ Ditto, seeds ripe 


— 


46 
















60 St Oks of ditto 


— 


84 





72,45 


5 


1 


13 


0,5 


3.05 


'il Spikes of ditto ... 


— 


16 
















62 Seeds of ditto ... 


— 


10 


—— 


62 


36 





I 


0,12 


0,88 


63 Chaff of barley (liordeum vulgart) 


— 


42 





20 


7,75 


12,5 


57 


0.5 


2,25 


64 Seeds of ditto 


— 


18 





29 


32,5 




35,5 


0,25 


2,8 


f)5 Ditto ..... 


— 


— 





23 


22 




21 


0,12 


29,88 


56 Oats 


— 


31 





I 


24 




60 


0.25 


14,75 


67 Leaves of rhododendron ferruginewn, 




















raised on Jura, a limestone moun- 




















1 tain, June 20 . . . 


— 


30 





23 


14 


43,25 


0,75 


15,53 


15,63 


68 Ditto, raised on Breven, a granitic 




















mountain, June 27 . - 


— 


25 


— 


21,1 


16,75 


16,75 


2 


5,77 


31,52 


69 Branches of ditto, June, 20 


— 


8 





22,5 


10 


39 


0,5 


5,4 


22.48 


70 Spikes of ditto, June 27 - 


— 


8 





24 


11,5 


'29 


1 


U 


34,5 


71 Leaves of fir {pinus abies), raised on 












1 








Jura, June 20 - . - 


— 


29 





16 


12,27 


43,5 


2.5 


1,6 


24,13 


72 Ditto, raised on Breven, June 27 


— 


20 





15 


12 


29 


19 


5,5 


19,5 


73 Branches of pine, June 20 


— 


15 


— 


15 












74 Whortleberry {vaccinium myrtillui) 




















raised on Jura, Aug. 29 


— 


26 




17 


18 


42 


0,5 


3,12 


19,38 


(75 Ditto, raised on Breven - 


— 


22 





I24 


22 


22 


5, 


9,5 


17,S 



C 106 ] . < 

Besides the principles, the nature of wh'ch has 
been just discussed, ©thers have been described by 
chemists as belonging to the vegetable kingdom : thus 
a substance, somewhat analogous to the muscular 
fibre of animals, has been detected by Vauquelin in 
the papaw ; and a matter similar to animal gelatine by 
Braconnot in the mushroom ; but in this place it 
would be improper to dwell upon peculiarities ; my 
object being to offer such general views of the consti- 
tution of vegetables as may be of use to the agricul- 
turist. Some distinctions have been adopted by sys- 
tematical authors which I have not entered into, be- 
cause they do not appear to me essential to this enquiry. 
Dr. Thomson, in his elaborate and learned system of 
chemistry, has described six vegetable substances, 
which he calls mucus, jelly, sarcocol, asparagin, inu- 
lin, and ulmin. He states that mucus exists in its 
purest form in linseed ; but Vauquelin has lately 
shewn, that the mucilage of linseed is, in its essential 
characters, analogous to gum ; but that it is combin- 
ed with a substance similar to animal mucus : vegeta- 
ble jelly. Dr. Thomson himself considers as a modifi- 
cation of gum. It is probable, from the taste of sar- 
cocol, that it is gum combined with a little sugar. 
Inulin is so analogous to starch, that it is probably a 
variety of that principle ; ulmin has been lately shewn 
by Mr. Smithson to be a compound of a peculiar ex- 
tractive matter and potassa ; and asparagin is proba- 
bly a similar combination. If slight differences in 
chemical and physical properties be consided as suffi- 
cient to establish a difference in the species of vegeta- 
ble substances, the catalogue of them might be enlar- 



C 107 1 

ed to almost any extent. No two compounds procured 
from different vegetables are precisely alike j and 
there are even differences in the qualities of the same 
compound, according to the time in which it has been 
collected, and the manner in which it has been pre- 
pared : the great use of classification in science is to 
assist the memory ; and it ought to be founded upon 
the similarity of properties which are distinct, charac- 
teristic, and invariable. 

The analysis of any substance containing mix- 
tures of the different vegetable principles, may be 
made in such a manner as is necessary for the views 
of the agriculturist with facility. A given quantity, 
say 200 grains, of the substance should be powdered, 
made into a paste or mass, with a small quantity of 
water, and kneaded in the hands, or rubbed in a mor- 
tar for some time under cold water ; if it contain 
much gluten, that principle will separate in a coherent 
mass. After this process, whether it has afforded 
gluten or not, it should be kept in contact with half a 
pint of cold water for three or four hours, being; oc- 
casionally rubbed or agitated : the solid matter should 
be separated from the fluid by means of blotting pa- 
per : the fluid should be gradually heated j if any 
flakes appear, they are to be separated by the same 
means as the solid matter in the last process, i. e. by 
filtration. The fluid is then to be evaporated to dry- 
ness. The matter obtained is to be examined by ap- 
plying moist paper, tinged with red cabbage juice, or 
violet juice to it ; if the paper become red, it contains 
acid matter ; if it become green, alkaline matter ; and 



C 108 J 

the nature of the acid or alkaline matter may be 
known by applying the tests described page 97,98,100. 
If the solid matter be sweet to the taste, it must be 
supposed to contain sugar ; if bitterish, bitter prin- 
ciple, or extract ; if astringent, tannin : and if it be 
nearly insipid, it must be principally gum or mucilage. 
To separate gum or mucilage from the other princi- 
ples, alcohol must be boiled upon the solid matter, 
which will dissolve the sugar and the extract, and 
leave the mucilage ; the weight of w^hich may be as- 
certained. ^ 

To separate sugar and extract, the alcohol must 
be evaporated till crytals begin to fall down, which are 
sugar ; but they will generally be coloured by some 
extract, and can only be purified by repeated solu- 
tions in alcohol. Extract may be separated from su- 
gar by dissolving the solid, obtained by evaporation 
from alcohol, in a small quantity of water, and boiling 
it for a long while in contact with the air. The ex- 
tract will gradually fall down in the form of an insoIii= 
ble power, and the sugar will remain in solution. 

If tannin exist in the first solution made by cold 
water, its separation is easily effected by the process 
described page 83. The solution of isinglass must be 
gradually added, to prevent the existence of an excess 
of animal jelly in the solution, which might be mista- 
ken for mucilage. 

When the vegetable substance, the subject of ex- 
periment, will afford no more principles to cold water, 
it must be exposed to boiling water. This will unite 
to starch if there be any, and may likewise take up 



C 109 ] 

iiiore sugar, extract, and tannin, provided they be In- 
timately combined with the other principles of the 
compound. 

The mode of separating starch is similar to that 
of separating mucilage. 

If after the action of hot water any thing remain, 
the action of boiling alcohol is then to be tried. This 
will dissolve resinous matter ; the quantity of which 
may be known by evaporating the alcohol. 

The last agent that may be applied is ether, 
which dissolves elastic gum, though the application is 
scarcely ever necessary ; for if this principle be pre- 
sent, it may be easily detected by its peculiar qualities. 

If any fixed oil or wax exist in the vegetable 
substance, it will separate during the process of boil- 
ing in water, and may be collected. Any substance 
not acted upon by water, alcohol, or ether, must be 
regarded as woody fibre. 

If volatile oils exist in any vegetable substances, 
it is" evident they may be procured, and their quantity 
ascertained, by distillation. 

When the quantity of fixed' saline, alkaline, met- 
allic, or e_arthy matter in any vegetable compound is 
to be ascertained, the compound must be decomposed 
by heat, by exposing it. if a fixed substance, in a cru- 
cible, to a long continued red heat ; and if a vola= 
tile substance, by passing it through an ignited porce- 
lain tube. The nature of the matter so produced, 
may be learnt by applying the tests mentioned in 
page 103, 



C 110 ] 

The only analyses In which the agricultural che- 
mist can often wish to occupy himself, are those of 
substances containing principally starch, sugar, gluten, 
oils, mucilage, albumen, and tannin. 

The two following statements will afford an idea 
of the manner in which the results of experiments 
may be arranged. 

The first is a statement of the composition of 
ripe peas, deduced from experiments made by Einhof ; 
the second are of the products afforded by oak bark, 
deduced from experiments conducted by myself. 

parts.' 
3840 parts of ripe peas afford, of starch 1 265 

Fibrous matter analogous to starch, ] 
with the coats of the peas J 

A substance analogous to gluten 550 

Mucilage - - - - 249 

Saccharine matter - - - 81 

Albumen - - - - 66 

Volatile matter - - - 540 

Earthy phosphates - - - 1 1 

Loss - • - - - - 22C| 
1000 parts of dry oak bark, from a small tree 
deprived of epidermis, contain. 

Of woody fibre - - - - 876 

— tannin ----- 57 

— extract ----- 31 

— mucilage - - - - - 18 

— matter rendered insoluble during evapor-"! 

ation, probably a mixture of albumen )> 9 
and extract - - - . J 

— loss, partly saline matter - - SO 



[ 111 3 

To ascertain the primary elements of the dif- 
ferent vegetable principles, and the proportions in 
which they are combined, different methods of analy- 
sis have been adopted. The most simple are their de- 
composition by heat, or their formation into new pro- 
ducts by combustion. 

When any vegetable principle is acted on by a 
strong red heat, its elements become newly arranged. 
Such of them as are volatile are expelled in the gas- 
eous form ; and are either condensed as fluids, or re- 
main permanently elastic. The fixed remainder is 
either carbonaceous, earthy, saline, alkaline, or metal- 
lic matter. 

To make correct experiments on the decomposi- 
tion of vegetable substances by heat, requires a com- 
plicated apparatus, much time and labour, and all the 
resources of the philosophical chemist ; but such re- 
sults as are useful to the agriculturist may be easily 
obtained. The apparatus necessary, is a green glass 
retort, attached by cement to a receiver, connected 
with a tube passing under an inverted jar of known 
capacity, filled with water.* A given weight of the 
substance is to be heated to redness in the retort over 
a charcoal fire ; the receiver is to be kept cool, and 
the process continued as long as any elastic matter is 
generated. The condensible fluids will collect in the 
receiver, and the fixed residuum will be found in the 
retort. The fluid products of the distillation of vege- 
table substances are principally water, with some 

' See Fig. 14. 



L 112 ] 

acetous and mucous acids, and empyreumatic oil, or 
tar, and in some cases ammonia. The gasses are car- 
bonic acid gas, carbonic oxide, and carburetted hydro- 
gene ; sometimes with olefiant gas, and hydrogene ; 
and sometimes, but more rarely, with azote. Car- 
bonic acid is the only one of those gasses rapidly ab- 
sorbed by water ; the rest are inflammable ; olefiant 
gas burns with a bright white light ; carburetted hy- 
drogene with a light like wax ; carbonic oxide with a 
feeble, blue flame. The properties of hydrogene and 
azote have been described in the last Lecture. The 
specific gravity of carbonic acid gas, is to that of air 
as 20.7 to 13.7, and it consists of one proportion of 
carbon 11.4, and two of oxygene 30. The specific 
gravity of gaseous oxide of carbon, is taking the same 
standard 13.2, and it consists of one proportion of 
carbon, and one of oxygene. 

The specific gravities of carburetted hydrogene and 
olefiant gas are respectively 8 arid 13 ; both contain 
four proportions of hydrogene ; the first contains one 
proportion, the second two proportions of carbon. 

If the weight of the carbonaceous residuum be 
added to the weight of the fluids condensed in the 
receiver and they be subtracted from the whole weight 
of the substance, the remainder will be the weight of 
the gaseous matter. 

The acetous and mucous acids, and the ammonia 
formed are usually in very small quantitities ; and by 
comparing the proportions of water and charcoal with 
the quantity of the gasses, taking into account their 
qualities, a general idea may be formed of the compo" 
sition of the substance. The proportions of the ele- 



C 113 ] 

I 

ments in the greater number of the vegetable sub- 
stances which can be used as food, have been ah*eady 
ascertained by philosophical chemists, and have been 
stated in the preceding pages ; the analysis by distil- 
lation may, however, in some cases, be useful in esti- 
mating the powers of manures in a manner that will 
be explained in a future lecture. 

The statements of the composition of vegetable 
substances, quoted from M. M. Gay Lussac and Then- 
ard were obtained by these philosophers by exposing 
the substances to the action of heated hyper-oxymu- 
riate of potassa 5 a body that consists of potassium, 
chlorine, and oxygene; and which afforded oxygene to 
the carbon and the hydrogene. Their experiments 
were made in a peculiar apparatus, and required great 
caution, and were of a very delicate nature. It will 
not therefore be necessary to enter upon any details 
of them. 

It is evident from the whole tenor of the state- 
ments which have been made, that the most essential 
vegetable substances consist of hydrogene, carbon, 
and oxygene in different proportions generally alone, 
but in some few cases combined with azote. The 
acids, alkalies, earths, metallic oxides, and saline com- 
pounds, though necessary in the vegetable oeconomy, 
must be considered as of less importance, particularly 
in their relation to agriculture, than the other princi- 
ples : and as it appears from M. de Saussure's table, 
and from other experiments, they differ in the same 
species of vegetable when it is raised on different soils. 

Q 



[ 114 ] 

M. M. Gay Lussac and Thenard have deduced 
three propositions, which they have called laws from 
their experiments on vegetable substances. The first 
is, " that a vegetable substance is always acid when- 
ever the oxygene it contains is to the hydrogene in a 
greater proportion than in water." 

The second, " that a vegetable substance is always 
resinous or oily or spirituous whenever it contains 
oxygene in a smaller proportion to the hydrogene than 
exists in water.'* 

The third, " that a vegetable substance is neither 
acid nor resinous ; but is either saccharine or mucila- 
ginous, or analogous to woody fibre or starch, when- 
ever the oxygene and hydrogene in it are in the same 
proportions as in water." 

New experiments upon other vegetable sub- 
stances, besides those examined by M. M. Gay Lussac 
and Thenard, are required before these interesting 
conclusions can be fully admitted. Their researches 
establish, however, the close analogy between several 
vegetable compounds differing in their sensible quali- 
ties, and combined with those of other chemists, offer 
simple explanations of several processes in nature and 
art, by which different vegetable substances are con- 
verted into each other, or changed into new com- 
pounds. 

Gum and sugar afford nearly the same elements 
by analysis : and starch differs from them only in con- 
taining a little more carbon. The peculiar properties 
of gum and sugar must depend chiefly upon the dif- 
ferent arrangement, or degree of condensation of their 



C 115 3 

elements ; and it would be natural to conceive from 
the composition of these bodies, as well as that of 
starch that all three would be easily convertible one 
into the other ; which is actually the case. 

At the time of the ripening of corn, the saccha- 
rine matter in the grain, and that carried from the sap 
A'essels into the grain, becomes coagulated, and forms 
starch. And in the process of malting, the converse 
change occurs. The starch of grain is converted into 
sugar. As there is a little absorption of oxygene, and a 
formation of carbonic acid in this case, it is probable 
that the starch loses a little carbon, which combines 
with the oxygene to form carbonic acid ; and probably 
the oxygene tends to acidify the gluten of the grain, 
and thus breaks down the texture of the starch ; gives 
a new arrangement to its elements, and renders it so- 
luble in water. 

Mr. Cruikshank, by exposing syrup to a sub- 
stance named phosphuret of lime, which has a great 
tendency to decompose water, converted a part of the 
sugar into a matter analogous to mucilage. And M. 
KirchhofF, recently, has converted starch into sugar by 
a very simple process, that of boiling in very diluted 
sulphuric acid. The proportions are 100 parts of 
starch, 400 parts of water, and 1 part of sulphuric 
acid by weight. This mixture is to be kept boiling 
for 40 hours ; the loss of water by evaporation being 
supplied by new quantities. The acid is to be neu- 
tralized by lime ; and the sugar crystallized by cool- 
ing. This experiment has been tried with success by 
many persons. Dr. Tuthill, from a pound and a half 



C 116 1 

of potatoe starch, procured a pound and a quarter of 
crystalline, brown sugar ; \which he conceives posses- 
sed properties intermediate between cane sugar, and 
grape sugar. 

It is probable that the conversion of starch into 
sugar is effected merely by the attraction of the acid 
for the elements of sugar ; for various experiments 
have been made, which prove that the acid is not de- 
composed, and that no elastic matter is set free ; pro- 
bably the colour of the sugar is owing to the disen- 
gagement, or new combination of a little carbon, the 
slight excess of which, as has been just stated, consti- 
tutes the only difference perceptible by analysis be- 
tween sugar and starch. 

M. Bouillon la Grange, by slightly roasting starch 
has rendered it soluble in cold water ; and the solu- 
tion evaporated afforded a substance, having the 
characters of mucilage. 

Gluten and albumen differ from the other vege- 
table products, principally by containing azote. When 
gluten is kept long in water it undergoes fermenta- 
tion ; ammonia (which contains its azote) is given off 
with acetic acid : and a fatty matter, and a substance 
analogous to woody fibre remain. 

Extract, tannin, and gallic acid, when their solu- 
tions are long exposed to air, deposit a matter similar 
to woody fibre ; and the solid substances are render- 
ed analogous to woody fibre by slight roasting ; and in 
these cases it is probable that part of their oxygene 
and hydrogene is separated as water. 



[ in ] 

All the other vegetable principles differ from the 
vegetable acids in containing more hydrogene and car- 
bon, or less oxygene ; many of them therefore are 
easily converted into vegetable acids by a mere sub- 
traction of some proportions of hydrogene. The ve- 
getable acids, for the most part, are convertible into 
each other by easy processes. The oxalic contains 
most oxygene ; the acetic the least : and this last sub- 
stance is easily formed by the distillation of other ve- 
getable substances, or by the action of the atmosphere 
on such of them as are soluble in water ; probably 
by the mere combination of oxygene with hydrogene 
and carbon, or in some cases by the subtraction of a 
portion of hydrogene. 

Alcohol, or spirits of wine, has been often men- 
tioned in the course of these Lectures. This sub- 
stance was not described amongst the vegetable princi- 
ples, because it has never been found ready formed in 
the organs of plants. It is procured by a change in 
the principles of saccharine matter, in a process called 
vinous fermentation. 

The expressed juice of the grape contains sugar, 
mucilage, gluten, and some saline matter, principally 
composed of tartaric acid : when this juice, or must, 
as it is commonly called, is exposed to the tempera- 
ture of about 70°, the fermentation begins ; it be- 
comes thick and turbid ; its temperature increases, and 
carbonic acid gas is disengaged in abundance. In a 
few days the fermentation ceases ; the solid matter 
that rendered the juice turbid falls to the bottom, and 
it clears ; the sweet taste of the fluid is in great mea- 
sure destroyed, and it is become spirituous. 



C 118 ] 

Fabroni has shewn that the gluten in must is 
essential to fermentation ; and that chemist has made 
saccharine matter ferment, by adding to its solution 
in water, common vegetable gluten and tartaric acid. 
Gay Lussac has demonstrated that must will not fer- 
ment when freed from air by boiling, and placed out 
of the contact of oxygene , but that fermentation be- 
gins as soon as it is exposed to the oxygene of air, a 
little of that principle being absorbed ; and that it then 
continues independent of the presence of the atmos- 
phere. 

In the manufacture of ale and porter, the sugar 
formed during the germination of barley is made to 
ferment by dissolving it in water with a little yeast, 
which contains gluten in the state proper for produc- 
ing fermentation, and exposing it to the requisite tem- 
perature ; carbonic acid gas is given off as in the 
fermentation of must, and the liquor gradually be- 
comes spirituous. 

Similar phenomena occur in the fermentation of 
the sugar in the juice of apples, and other ripe fruits. 
It appears that fermentation depends entirely upon a 
new arrangement of the elements of sugar ; part of 
the carbon uniting to oxygene to form carbonic acid, 
and the remaining carbon, hydrogene, and oxygene 
combining as alcohol ; and the use of the gluten or 
yeast, and the primary exposure to air seems to be to 
occasion the formation of a certain quantity of car- 
bonic acid ; and this change being once produced is 
continued ; its agency may be compared to that of a 
spark in producing the inflammation of gunpowder ; 



C 119 ] 

the increase of temperature occasioned by the forma- 
tion of one quantity of carbonic acid occasions the 
combination of the elements of another quantity. 

The results obtained by different chemists in ex- 
periments on the analysis of alcohol differ so much, 
that no general conclusions can be drawn from them. 
If it be supposed that one proportion of carbonic acid 
is formed in the fermentation of sugar ; then accord- 
ing to Dr. Thomson's analysis of sugar, which gives 
its composition as 3 proportions of carbon, 4 of oxy- 
gene, and 8 of hydrogene, alcohol would consist of 
2 proportions of carbon, 2 of oxygene, and 8 of hy- 
drogene ; and it might be considered as containing the 
same elements as two proportions of defiant gas, with 
two proportions of oxygene. 

Alcohol in its purest known form, is a highly 
inflammable liquid, of specific gravity 796, at the 
temperature of 60° ; it boils at about 170° Fahrenheit. 
This alcohol is obtained by repeated distillation of the 
strongest common spirit from the salt called by che- 
mists muriate of lime, it having been previously heat- 
ed red hot. 

The strongest alcohol obtained by the distillation 
of spirit without salts, has seldom a less specific gravi- 
ty than 825 at 60°; and it contains, according to 
Lowitz*s experiments, 89 parts of the alcohol of 796, 
and 1 1 parts of water. The spirit established as proof 
spirit by act of parliament passed in 1762, ought to 
have the specific gravity of 916; and this contains 
nearly equal weights of pure alcohol and water. 



[ 120 ] 

The alcohol in fermented liquors is in combina- 
tion with water, colouring matter, sugar, mucilage, 
and the vegetable acids. It has been often doubted 
whether it can be procured by any other process J:han 
distillation ; and some persons have even supposed 
that it is formed by distillation. The recent experi- 
ments of Mr. Brande are conclusive against both 
these opinions. That gentleman has shewn that the 
colouiing and acid matter in wines may be, for the 
most part, separated in a solid form by the action of a 
solution of sugar of lead (acetate of lead), and that the 
alcohol may be then obtained by abstracting the water 
by means of hydrate of potassa or muriate of lime, 
without artificial heat. 

The intoxicating powers of fermented liquors 
depend on the alcohol that they contain ; but their 
action on the stomach is modified by the acid, saccha- 
rine, or mucilaginous substances they hold in solu- 
tion. Alcohol probably acts with more efficacy when 
it is most loosely combined ; and its energy seems to 
be impaired by union with large quantities of water, 
or with sugar or acid, or extractive matter. 

The following table contains the results of Mr. 
Brande's experiments on the quantity of alcohol of 
825 at 60°, in different fermented liquors. 



121 



V 


Proportion of 




Proportion of 


"Wine. 


Alcohol, per 


Wine. 


Alcohol, per 




Cent, by Mea- 




Cent, by Mea- 




sure. 




sure. 


Port 


21,40 


White Hermitage - 


17,43 


Ditto 


22,30 


Red Hermitage 


12,32 


Ditto . 


23,39 


Hock - 


14,37 


Ditto 


23,71 


Ditto 


8,88 


Ditto 


24,29 


Vin de Grave • 


12,80 


Ditto - 


25,83 


Frontignac 


12,79 


Madeira 


19,34 


Coti P..oti 


12,32 


Ditto 


21,40 


RousiUon 


17,26 


Ditto 


23,93 


Cape Madeira 


18,11 


Ditto 


24,42 


Cape Muschat 


18,25 


Sherry - 


18,25 


Constaiilia 


19,75 


Ditto 


18,79 


Tent 


13,30 


Ditto 


19,81 


Sheraaz 


15,52 


Ditto 


19,83 


Syracuse 


15,23 


Claret - 


12,91 


Nice 


14,63 


Ditto 


14,03 


Tokay - 


9,88 


Ditto 


16,32 


Raisin Wine - 


25,77 


Calcavella 


18,10 


Grape Wine - 


18,11 


Lisbon . - . 


18.94 


Currant Wine 


20.55 


Malaga - 


17,26 


Gooseberry Wine - 


11,84 


Bucellas 


18,49 


Elder Wine - 


9,87 


Red Madeira - 


18.40 


Cyder - 


9,87 


Malmsey Madeira - 


16,40 


Perry 


9,S7 
6,80 


Marsala 


25,37 


Brown Stout - 


Ditto 


17,26 


Ale - - - 


8,83 


Red Champagne 


11,30 


Brandy - 


53,39 


White Champagne - 


12,80 


Rum 


53,68 


Burgundy 


14,53 


Hollands 


51,60 


Ditto 


11,95 







The spirits distilled from diiFerent fermented 
liquors differ in their flavour : for peculiar odorous 
matter, or volatile oils, rise in most cases with the al- 
cohol. The spirit from malt usually has an empy- 
reumatic taste like that of the oil, formed by the dis- 
tillation of vegetable substances. The best brandies 
seem to owe their flavour to a peculiar oily matter, 
formed probably by the action of the tartaric acid on 
alcohol ; and rum derives its characteristic taste from 
a principle in the sugar cane. All the common spirits 
may, I find, be deprived of their peculiar flavour by 
repeatedly digesting them with a mixture of well burnt 



[ 122 ] 

charcoal and quicklime ; they then afford pure alco- 
hol by distillation. The cognac brandies, I find, con- 
tain vegetable prussic acid, and their flavour may be 
imitated by adding to a solution of alcohol in water of 
the same strength, a few drops of the ethereal oil of 
wine produced during the formation of ether,* and a 
similar quantity of vegetable prussic acid procured 
from laurel leaves or any bitter kernels. 

I have mentioned ether in the course of this Lec- 
ture ; this substance is procured from alcohol by distil- 
ling a mixture of equal parts of alcohol and sulphuric 
acid. It is the lightest known liquid substance, being 
of specific gravity 632 at 60". It is very volatile, and 
rises in vapour even by the heat of the body. It is 
highly inflammable. In the formation of ether it is 
most probable that carbon and the elements of water 
are separated from the alcohol, and that ether differs 
from alcohol in containing less oxygene and carbon \ 
but its composition has not yet been accurately ascer- 
tained. Like alcohol it possesses intoxicating powers. 

A number of the changes taking place in the ve- 
getable principles depend upon the separation of oxy- 
gene and hydrogene as water from the compound ; 
but there is one of very great importance, in which a 
new combination of the elements of water is the prin- 
cipal operation. This is in the manufacture of bread. 
When any kind of flour, which consists principally of 



• In the i<rocess of the distillation of alcohol and sulphuric acid after the ether 
is procured; by a higher degree of heat, a yellow fluid is produced, which is ths- 
Substance in question. It has a fragrant smell and an agreeable taste. 



[ 123 ] 

starch, is made into a paste with water, and immedi- 
ately and gradually heated to about 440°, it increases 
in weight, and is found entirely altered in its proper- 
ties ; it has lost its solubility in water, and its power 
of being converted into sugar. In this state it is un- 
leavened bread. 

When the fiour of corn or the starch of potatoes, 
mixed with boiled potatoes, is made into a paste with 
water, kept warm, and suffered to remain 30 or 40 
hours, it ferments, carbonic acid gas is disengaged 
from it, and it becomes filled with globules of elastic 
fluid. In this state it is raised dough, and affords by 
baking, leavened bread ; but this bread is sour and 
disagreeable to the taste j and leavened bread for use 
is made by mixing a little dough, that has fermented, 
with new dough, and kneading them together, or by 
kneading the bread with a small quantity of yeast. 

In the formation of wheaten bread more than 1 -4 
of the elements of water combine with the flour ; 
more water is consolidated in the formation of bread 
from barley, and still more in that from oats ; but 
the gluten in wheat, being in much larger quantity 
than in other grain, seems to form a combination with 
the starch and water, which renders wheaten bread 
more digestible than the other species of bread. 

The arrangement of many of the vegetable prin- 
ciples in the different parts of plants has been inciden- 
tally mentioned in this Lecture j but a more particular 
statement is required to afford just views of the rela- 
tion between their organization and chemical constitu- 
*ion, which is an object of great importance. The 



[ 124 ] 

tubes and hexagonal cells in the vascular system of 
plants are composed of woody fibre ; and when they 
are not filled with fluid matter they contain some of 
the solid materials which formed a constituent part of 
the fluids belonging to them. 

In the roots, trunk, and branches, the bark, al- 
burnum, and heartwood, the leaves and flowers ; the 
great basis of the solid parts is woody fibre. It forms 
by far the greatest part of the heart wood and bark ; 
there is less in the alburnum, and still less in the leaves 
and flowers. The alburnum of the birch contains so 
much sugar and mucilage, that it is sometimes used 
in the North of Europe as a substitute for bread. The 
leaves of the cabbage, broccoli, and seacale, contain 
much mucilage, a little saccharine matter and a little 
albumen. From a 1000 parts of the leaves of com- 
mon cabbage I obtained 41 parts of mucilage, 24 of 
sugar, and 8 of albuminous matter. 

In bulbous roots, and sometimes in common 
roots, a large quantity of starch, albumen, and mucil- 
age, are often found deposited in the vessels ; and 
they are most abundant after the sap has ceased to 
flow : and afford a nourishment for the early shoots 
made in spring. The potatoe is the bulb that contains 
the largest quantity of soluble matter in its cells and 
vessels ; and it is of most importance in its appli- 
cation as food. Potatoes in general afford from ' to a 
their weight of dry starch. From 100 parts of the 
common Kidney potatoes^ Dr. Pearson obtained from 
:32 to 28 parts of meal, which contained from 23 to 
20 of starch and mucilage : and 100 parts of the Ap" 



C 125 ] 

pie potatoe in various experiments, afforded me from 
18 to 20 parts of pure starch. From five pounds of 
the variety of the potatoe called Captain hart, Mr. 
Skrimshire, jun. obtained 12 oz. of starch, from the 
same quantity of the Rough red potatoe 104 oz., from 
the Moulton white 111, from the Torkshire kidney 
10| oz., from Hundred eyes 9 oz., from Purple red 8'-, 
from Ox noble Sj. The other soluble substances in 
the potatoe are albumen and mucilage. 

From the analysis of Einhoff it appears that 7680 
parts of potatoes afford 

Of starch - - - - 1153 

— Fibrous matter analogous to starch 540 

— Albumen - - - - 107 

— Mucilage in the state of a saturated') 

solution - - - - J 

2112 
So that a fourth part of the weight of the potatoe at 
least may be considered as nutritive matter. 

The turnip, carrot, and parsnip, afford principally 
saccharine, mucilaginous, and extractive matter. I 
obtained from 1000 parts of common turnips 7 parts 
of mucilage, 34 of saccharine matter, and nearly 1 
part of albumen. 1000 parts of carrots furnished 
95 parts of sugar. 3 parts of mucilage, and ^ part of 
extract ; 1000 parts of parsnip afforded 90 parts of 
saccharine matter, and 9 parts of mucilage. The 
Walcheren or white carrot, gave in 1000 parts, 98 
parts of sugar, 2 parts of mucilage, and 1 of extract. 



C 126 ] 

Fruits, In the organization of their soft parti>, 
approach to the nature of bulbs. They contain a cer- 
tain quantity of nourishment laid up in their cells for 
the use of the embryon plant ; mucilage, sugar, starch 
are found in many of them often combined with vege- 
table acids. Most of the fruit trees common in Bri- 
tain have been naturalized on account of the saccha- 
rine matter they contain, which, united to the vegeta-- 
ble acids and mucilage, renders them at once agreea-' 
ble to the taste and nutritive. 

The value of fruits for the manufacture of fer- 
mented liquors may be judged of from the specific 
gravity of their expressed juices. The best cyder and 
perry are made from those apples and pears that af- 
ford the densest juices ; and a comparison between 
different fruits may be made with tolerable accuracy 
by plunging them together into a saturated solution of 
salt, or a strong solution of sugar j those that sink 
deepest will afford the richest juice. 

Starch or coagulated mucilage forms the greatest 
part of the seeds and grains used for food ; and they 
are generally combined with gluten, oil, or albumin- 
ous matter. In corn, with gluten, in peas and beans, 
with albuminous matter ; and in rape-seed, hemp- 
seed, linseed, and the kernels of most nuts, with oils. 

I found lOO parts of good full grained wheat 
sown In autumn to afford 

Of Starch - - - 77 
— Gluten - - - 19 
100 parts of wheat sown in spring, 

Of starch - - - 70 
--Gluten " 24 



[ 127 3 

100 parts of Barbary wheat. 

Of starch . - - 47 

— Gluten - - 23 
100 parts of Sicilian wheat. 

Of starch - - . 75 

— Gluten - - - 21 

I have examined different specimens of North 
American wheat, all of them have contained rather 
more gluten than the British. In general the wheat 
of warm climates abounds more in gluten, and in in- 
soluble parts ; and it is of greater specific gravity, 
harder, and more difficult to grind. 

The wheat of the south of Europe, in conse- 
quence of the larger quantity of gluten it contains, is 
peculiary fitted for making macaroni, and other pre- 
parations of flower in which a glutinous quality is con- 
sidered as an excellence. 

In some experiments made on barley, I obtained 
from 100 parts of full and fair Norf©lk barley. 
Of Starch . . - 79 

— Gluten - - - 6 

— Husk - - - 8 
The remaining 7 parts saccharine matter. 

EinhofF has published a minute analysis of barley 
meal. He found in 3340 parts. 

Of volatile matter - - - 360 
— • Albumen - - - - 44 

— Saccharine matter - - 200 

— Mucilage . - - . 176 

— Phosphate of lime, with some albumen 9 
= Gluten - - - - 135 



C 128 J 

Of Husk, with some gluten and starch 260 

— Starch not quite free from gluten ^580 

— Loss ----- 78 
Rye afforded to Einhoff, in 3840 parts ; 2520 

meal, 930 husk, and 390 moisture j and the same 
quantity of meal analysed gave, 

Of Starch . - . . 2345 

— Albumen - - . . 126 

— Mucilage - - - - 426 

— Saccharine matter - - 126 
. — Gluten not dried - - 364 

Remainder husk and loss. 

I obtained from 100 parts of rye, grown in Suf- 
folk, 61 parts of starch, and 5 parts of gluten. 

100 parts of oats, from Sussex, afforded me 59 
parts of starch, 6 of gluten, and 2 of saccharine mat- 
ter. 

1000 parts of peas, grown in Norfolk, afforded 
me 501 parts of starch, 22 parts of saccharine matter, 
35 parts of albuminous matter and 1 6 parts of ex- 
tract, which became insoluble during evaporation of 
the saccharine fluid. 

From 3840 parts of marsh beans fViciafabaJ, 
Einhoff obtained. 

Of Starch - - - - 1312 

— Albumen - - - - 31 

— other matters which may be con-l 

ceived nutritive ; such as gum- } 
my, starchy, fibrous matter aii- j . 
alogous to animal matter J 



C 129 ] 

The same quantity of kidney beans (Phaseolus 
^vulgaris) afforded, 

Of matter analogous to starch - 1 805 
— ' Albumen and matter approaching I 

to animal matter in its nature J ^^^ 
— Mucilage - - - - 799 

From 3840 parts of lentiles he obtained 1260 
parts of starch, and 1433 of a matter analogous to 
animal matter. 

The matter analogous to animal matter is des- 
cribed by Einhoff ; as a glutinous substance insoluble 
in water ; soluble in alcohol when dry, having the ap- 
pearance of glue ; probably a peculiar modification of 
gluten. 

From 16 parts of hemp-seeds Bucholz obtained 
3 parts of oil, 3i parts of albumen, about 1? of sac- 
charine and gummy matter. The insoluble husks 
and coats of the seeds weighed 61 parts. 

The different parts of flowers contain different 
substances : the pollen, or impregnating dust of the 
date, has been found by Fourcroy and Vauquelin to 
contain a matter analogous to gluten, and a soluble 
extract abounding in malic acid. Link found in the 
pollen of the hazle tree, much tannin and gluten. 

Saccharine matter is found in the nectarium of 
flowers, or the receptacles within the corolla, and by 
tempting the larger insects into the flowers, it renders 
the work of impregnation more secure ; for the pollen 
is often by their means applied to the stigma ; and 
this is particularly the case when the male and female 
organs are in different flowers or different plants. 



C 130 3 

It has been stated that the fragrance of flowers 
depends upon the volatile oils they contain ; and these 
oils, by their constant evaporation, surround the 
flower with a kind of odorous atmosphere ; which, at 
the same time that it entices larger insects, may pro- 
bably preserve the parts of fructification from the ra- 
vages of the smaller ones. Volatile oils, or odorous 
substances, seem particularly destructive to these mi- 
nute insects and animalcules which feed on the sub- 
stance of vegetables ; thousands of aphides may be 
Visually seen in the stalk and leaves of the rose ; but 
none of them are ever observed on the flower^ Cam- 
phor is used to preserve the collections of naturalists. 
The woods that contain aromatic oils are remarked 
for their indestructibility ; and for their exemption 
from the attacks of insects : this is particularly the 
case with the cedar, rose-wood, and cypress. The 
gates of Constantinople, which were made of this last 
wood, stood entire from the time of Constantine, their 
founder, to that of Pope Eugene IV. a period of 1 100 
years. 

The petals of many flowers afford saccharine and 
mucilaginous matter. The white lily yields mucilage 
abundantly ; and the orange lily a mixture of mucil- 
age and sugar ; the petals of the convolvulus afford 
sugar, mucilage, and albuminous matter. 

The chemical nature of the colouring matters of 
flowers has not as yet been subject to any very accu- 
rate observation. These colouring matters, in gen- 
eral, are very transient, particularly the blues and 
reds ; alkalies change the colours of most flowers to 
green, and acids to red. An imitation of the colour- 



C isi ] 

ing matter may be made by digesting solutions of gall- 
nuts with chalk: a green fluid is obtained, which be- 
comes red by the action of an acid; and has its green 
colour restored by means of alkalies. 

The yellow colouring matters of flowers are the 
most permanent; the carthamus contains a red and a 
yellow colouring matter; the yellow colouring matter 
is easily dissolved by water, and from the red, rouge 
is prepared by a process which is kept secret. 

The same substances as exist in the solid parts of 
plants are found in their fluids, with the exception of 
woody fibre. Fixed and volatile oils containing resin 
or camphor, or analogous substances in solution exist 
in the cylindrical tubes belonging to a number of 
plants. Different species of Euphorbia emit a milky 
juice, which when exposed to air deposit a substance 
analogous to starch, and another similar to gluten. 

Opium, gum elastic, gamboge, the poisons of the 
Upas Antiar and Tieute, and other substances that 
exude from plants, may be considered as peculiar 
juices belonging to appropriate vessels. 

The sap of plants, in general, is very compound 
in its nature; and contains most saccharine, mucilagin- 
ous, and albuminous matter in the alburnum; and 
most tannin and extract in the bark. The cambium, 
which is the mucilaginous fluid found in trees between 
the wood and the bark, and which is essential to the 
formation of new parts, seems to be derived from these 
two kinds of sap; and probably is a combination of 
the mucilaginous and albuminous matter of one, with 
the astringent matter of the Other, in a state fitted to 
become organized by the separation of its watery parts 



I 13^ ] 

The alburnous saps of some trees have been che- 
mically examined by Vauquelin. - He found in those 
of the elm, beech, yoke elm, hornbeam and birch, ex- 
tractive and mucilaginous matter, acetic acid combin- 
ed with potassa or lime. The solid matter afforded 
by their evaporation yielded an ammoniacal smell, pro- 
bably owing to albumen: the sap of the birch afforded 
saccharine matter. 

Deyeux in the sap of the vine and the yoke elm 
has detected a matter analogous to the curd of milk. 
I found a substance similar to albumen in the sap of 
the walnut tree. 

I found the juice which exudes from the vessels 
of the marshmallow when cut, to be a solution of 
mucilage. 

The fluids contained in the sap vessels of wheat 
and barley, afforded in some experiments which I made 
on them, mucilage, sugar, and a matter which coag- 
ulated by heat; which last was most abundant in wheat. 
The following table contains a statement of the 
quantity of soluble or nutritive matters contained in 
varieties of the different substances that have been 
mentioned, and of some others which are used as arti- 
cles of food, either for man or cattle. The analyses 
are my ownj and were conducted with a view to a 
knowledge of the general nature and quantity of the 
products, and not of their intimate chemical composi- 
tion. The soluble matters afforded by the grasses, 
except that from the fiorin in winter, were obtained 
by Mr. Sinclair, gardener to the duke of Bedford, 
from given weights of the grasses cut when the seeds 
were ripe J they were sent to me by his Grace's desire 



c 



133 



3 



for chemical examination; and form part of the results 
of an important and extensive series of experiments on 
grasses, made by direction of the Duke, at Woburn 
Abbey, the full details of which I shall hereafter have 
the pleasure of stating. 

Table of the Quantities of soluble or nutritive Matters 
afforded by 1000 parts of different vegetable Sub- 
stances. 





U-i u 








t. « c 




o > 




u 


i 


iiS.2 




>%'!i 


u 


*> 


.o 


HSH 




*•» *•> 


o 


u , 


< 


S S J; 


Vegetables or vegetable 
Substance. 


C 3 ,• 

0) " fl 


4) A 
3 « 




jct, or 
red in 
g evap< 




°1 


s 


■s 


a 


i-d.s 




•s 2, 




t) 


O 


>< S 3 




^ S 




in 




w 2-5 


Middlesex wheat, average 










crop - - . - 


955 


765 


— 


190 




Spring wheat 


940 


700 


— 


240 




Mildewed wheat of i805 


210 


178 


_ 


32 




Blighted wheat of 1804 


650 


520 


_ 


130 




Thick-skinned Sicilian 












wheat of 1810 


855 


725 


_ 


230 




Thin-skinued Sicilian 












wheat of 1810 - 


961 


722 


— , 


239 




Wheat from Poland 


950 


750 


— • 


200 




North American wheat 


955 


730 


_ 


225 




Norfolk barley 


920 


790 


70 


60 




Oats from Scotland 


743 


641 


15 


87 




Rye from Yorkshire 


792 


645 


38 


109 




Common bean 


570 


426 


_ 


103 


41 


Dry peas ... 


574 


501 


22 


35 


16 


Potatoes - . \ 


fl-Om 260 
to 200 


from 200 
to 155 


from 20 

to 15 


from 40 
to 30 




Linseed cake 


151 


123 


11 


17 




Red beet 


143 


14 


121 


13 




White beet 


136 


13 


119 


4 




Parsnip ... 


99 


9 


90 






Carrots 


98 


3 


95 






Common turnips - 


42 


7 


34 


1 




Swedish turnips - 


64 


9 


51 


2 


2 


Cabbage 


73 


41 


24 


8 




Broad-leaved clover 


39 


31 


3 


2 


3 


liong-rooted clover 


39 


30 


4 


3 


2 


White clover 


32 


29 


1 


3 


5 


Sainfoin 


39 


28 


2 


3 


6 


Lucerne 


23 


18 


1 


_ 


4 


Meadow fox-tail grass 


33 


24 


3 


_ 


e 


Perennial rye grass - 


39 


26 


4 


_ 


5 


1 Fertile meadow grass - 


78 


65 


6 


_ 


7 


Roughish meadow grass 


39 


29 


5 


_ 


6 


Crested dog's-tail grass 


35 


28 


3 


_ 


4 


Spiked fescue grass 


19 


15 


2 


— 




Sv/eet-scented soft grass 


82 


72 


4 


_ 


6 


1 Sweet-scented vernal grass 


50 


43 


4 


_ 


3 


1 Fiorin 


54 


46 


5 


I 


2 


J Fiorin cut in winter - 


76 


64 


S 


1 


3 



C 334 ] 

All these substances were submitted to experi- 
ment green, and in their natural states. It is probable 
that the excellence of the different articles as food 
will be found to be in a great measure proportional to 
the quantities of soluble or nutritive matters they 
afford; but still these quantities cannot be regarded as 
absolutely denoting their value. Albuminous or glutin- 
ous matters have the characters of animal substances; 
sugar is more nourishing, and extractive matter less 
nourishing, than any other principles composed of car- 
bon, hydrogene, and oxygene. Certain combinations 
likewise of these substances may be more nutritive 
than others. 

I have been informed by Sir Joseph Banks, that 
the Derbyshire miners in winter, prefer oat cakes to 
wheaten bread; finding that this kind of nourish- 
ment enables them to support their strength and per- 
form their labour better. In summer, they say oat 
cake heats them, and they then consume the finest 
wheaten bread they can procure. Even the skin of 
the kernel of oats probably has a nourishing power, 
and is rendered partly soluble in the stomach with the 
starch and gluten. In most countries of Europe, ex- 
cept Britain, and in Arabia, horses are fed with barley 
mixed with chopped straw; and the chopped straw 
seems to act the same part as the husk of the oat. In 
the mill 14lbs. of good wheat yield on an average 
ISlbs. of flour, the same quantity of barley 12lbs. and 
of oats only 8lbs. 

In the south of Europe, hard or thin-skinned 
wheat is in higher estimation, than soft or thick-skin- 



i 135 ] 

ned wheat: the reason of which is obvious^ from the 
larger quantity of gluten and nutritive matter it con- 
tains. I have made an analysis of only one specimen 
of thin-skinned wheat, so that othen specimens may 
possibly contain more nutritive matter than that in the 
Table: the Barbary and Sicihan wheats, before refer- 
red to, were thick-skinned wheats, in England the dif- 
ficulty of grinding thin-skinned wheat is an objection; 
but this difficulty is easily overcome by moistening the 
corn.* 



' For the following note on this subject I am indebted to the kindness of the 
Right Hon. Sir Joseph Banks, Bart. K. B. 
Infsrmation received from ^ohn Ifeffery, Esg. His Majesty's Consul Cenerai at Lisbon, 

in Ansnaer to Queries transmitted to him, from the Comm. of P. C.for Trade, 

dated ^an. 12, 1812. 

To grind hard corn with the mill-stones used in England, the wheat must bc^ 
well screened, then sprinkled with water at the miller's discretion, andlaid in heaps 
and frequently turned and thoroaghly mixedj which will soften the husk so as to 
make it separate from the flour in grinding, and of course give the flour a brighter 
colour; otherwise the flinty quality of the wheat, and the thinness of the skin will 
prevent its separation, and will render the ftour unfit for making into bread. 

I am informed by a miller of considerable experience, and who works his mills 
entirely with the stones from England or Ireland, that he frequently prepares the 
hard Barbary corn by immersing it in water in close wicker baskets, and spreading 
it thinly on a floor to dry; much depends on the judgment and skill of the milier in 
preparing thecorn for the mill according to its relative quality. I beg to observe, 
that it is not from this previous process of wetting thecorn that the weight in the 
flour of hard corn is encreased; bat from its natural quality it imbibei considerably 
more water in making it into broad. The mill-stones must not^be cut too deep, but 
the furrows very fine, and picked in the usual way. The mills should work with less 
velocity in grinding hard corn than with soft, and set to work at first with soft 
corn, till the mill ceases to work well; then put on the hard corn. Hard wheat al- 
ways sells at a higher price in the market than soft wheat, on an average of ten to 
fifteen percent; as it produces more flour in proportion, and less bran than ih? 
soft corn. 

Flour made from hard wheat is more esteemed than what is made from scfs 
corn and both sorts we applied to every purpose. 



[ 136 J 



LECTURE IV. 

On Soils: their constituent Parts, On the analysis of 
Soils. Of the Uses of the Soil. Of the Rocks and 
Strata found beneath Soils. Of the ijiiprovement 
of Soil. 

No subjects are of more importance to the far-* 
mer than the nature and improvement of soils; and no 
parts of the doctrines of agriculture are more capable 
of being illustrated by chemical enquiries. 

Soils are extremely diversified in appearance and 
quality; yet as it was stated in the introductory Lec- 
ture, they consist of different proportions of the same 
elements; v/hich are in various states of chemical com- 
bination, or mechanical mixture. 

The substances which constitute soils have been 
already mentioned. They are certain compounds of 
the earths, silica, lime, alumina, magnesia, and of the 
oxides of iron and manganesum; animal and vegetable 
matters in a decomposing state, and saline, acid or al- 
kaline combinations. 

In all chemical experiments on the composition 
of soils connected with agriculture, the constituent 



The flour of hard wheat is in general superior to that made from soft; and 
there is no difference in the process of making them into bread; but the flour from 
hard wheat will imbibe and retain more water in making into bread; and will con- 
sequently produce more weight of bread: it is the practice here, and which I am 
persuaded it would be adviseable to adopt in England, to make bread with flour of 
hard and soft wheat, which, by being mixed, will make the bread much better. 

(Signed) JOHN JEFFERY, 



C 137 j 

parts obtained are compounds; and they act as com- 
pounds in nature: it is in this state, therefore, that I 
shall describe their characteristic properties. 

1. Silica, or the earth of Jlints, in its pure and 
crystallized form, is the substance known by the name 
of rock crystal, or Cornish diamond. As it is procur- 
ed by chemists, it appears in the form of a white 
impalpable powder. It is not soluble in the common 
acids, but dissolves by heat in fixed alkaline lixivia. 
It is an incombustible substance, for it is saturated 
with oxygene. I have proved it to be a compound of 
oxygene, and the peculiar combustible body which I 
have named silicum; and from the experiments of Ber- 
zelius, it is probable that it contains nearly equal 
weights of these two elements. 

2. The sensible properties of lijne are well 
known. It exists in soils usually united to carbonic 
acid; which is easily disengaged from it by the attrac- 
tion of the common acids. It is sometimes found 
combined with the phosphoric and sulphuric acids. 
Its chemical properties and agencies in its pure state 
will be described in the Lecture on manures obtained 
from the mineral kingdom. It is soluble in nitric and 
muriatic acids, and forms a substance with sulphuric 
acid, difficult of solution, called gypsum. It is not 
soluble in alkaline solutions. It consists of one pro- 
portion 40 of the peculiar metallic substance, which I 
have named calcium; and one proportion 15 of oxy- 
gene. 

3. Alumina exists in a pure and crystallized state 
in the white sapphire, and united to a little oxide of 

T 



[ 138 ] 

iron and silica in the other oriental gems. In the state 
in which it is procured by chemists, it appears as a 
white ponder, soluble in acids and fixed alkaline li- 
quors. From my experiments, it appears that alumi- 
na consists of one proportion 33 of aluminum, and 
one 15 of oxygene. 

4. Magnesia exists in a pure crystallised state, 
constituting a mineral like talc found in North Ame- 
rica. In its common form it is the magnesia usta, or 
calcined magnesia of druggists. It generally exists in 
soils combined with carbonic acid. It is soluble in all 
the mineral acids; but not in alkaline lixivia. It is dis- 
tinguished from the other earths found in soils by its 
ready solubility in solutions of alkaline carbonates, 
saturated with carbonic acid. It appears to consist of 
38 magnesium and 15 oxygene. 

5. There are two well known oxides of iron, the 
black and the brown. The black is the substance that 
flies off when red hot iron is hammered. The brown 
oxide may be formed by keeping the black oxide red 
hot, for a long time in contact with air. The first 
seems to consist of one proportion of iron 103, and 
two of oxygene 30; and the second of one proportion 
of iron 103, and three proportions of oxygene 45. 
The oxides of iron sometimes exist in soils combined 
with carbonic acid. They are easily distinguished from 
other substances by their giving when dissolved in 
acids a black colour to solution of galls, and a bright 
blue precipitate to solution of prussiate of potassa and 

iron. 

6. The oxide of manganesum is the substance com- 
monly called manganese, and used in bleeching. It 



C 139 ] 

appears to be composed of one proportion of mangan^ 
ireum 113, and three of oxygene 45. It is distinguish- 
ed from the other substances found in soils, by its pro- 
perty of decomposing muriatic acid, and converting it 
into chlorine. 

7. Vegetable and animal patters are known by their 
sensible qualities, and by their property of being de- 
composed by heat. Their characters may be learnt 
from the details in the last Lecture. 

8. The saline co?npounds found in soils, are com- 
mon salt, sulphate of magnesia, sometimes sulphate of 
iron, nitrates of lime and of magnesia, sulphate of po- 
tassa, and carbonates of potassa and soda. To des- 
cribe their characters minutely will be unnecessary; the 
tests, for most of them have been noticed p. 103. 

The silica in soils is usually combined yjfiih alumi- 
na and oxide of iron, or with alumina, lime, magnesiaj, 
and oxide of iron, forming gravel and sand of differ- 
ent degrees of fineness. The carbonate of lime is 
usually in an impalpable form, but sometimes in the 
state of calcareous sand. The magnesia, if not com- 
bined in the gravel and sand of soil, is in a fine pow- 
der united to carbonic acid. The impalpable part of 
the soil, which is usually called clay or loam, consists 
of silica, alumina, lime, and magnesiaj and is, in fact, 
usually of the same composition as the hard sand, but 
more finely divided. The vegetable or animal, mat- 
ters, (and the first is by far the most common in soils) 
exist in different states of decomposition. They are 
sometimes fibrous, sometimes entirely broken down 
and mixed with the soil. 



[ 1-iO ] 

To form a just idea of soils, it is necessary to 
conceive different rocks decomposed, or ground into 
parts and powder of different degrees of fineness; 
some of their soluble parts dissolved by water, and 
that water adhering to the mass, and the whole mixed 
with larger or smaller quantities of the remains of ve- 
getables and animals, in different stages of decay. 

It will be necessary to describe the processes by 
which all the varieties of soils may be analysed. I 
shall be minute in these particulars, and, I fear, tedi- 
ous; but the philosophical farmer will, I trust, feel the 
propriety of full details on this subject. 

The instruments required for the analysis of soils 
are few, and but little expensive. They are a balance 
capable of containing a quarter of a pound of com- 
mon soil, and capable of turning when loaded, with 
a grain; a set of weights from a quarter of a pound 
Troy to a grain; a wire sieve, sufliciently coarse to ad- 
mit a mustard seed through its apertures; an Argand 
lamp and stand; some glass bottles; Hessian crucible; 
porcelain, or queen's ware evaporating basons; a 
Wedgewood pestle and mortar; some filtres made of 
half a sheet of blotting paper, folded so as to contain a 
pint of liquid, and greased at the edges; a bone knife, 
and an apparatus for collecting and measuring aeriform 
fluids. 

The chemical substances or reagents required 
for separating the constituent parts of the soil, have, 
for the most part, been mentioned before: they are 
muriatic acid {spirit of sali)^ sulphuric acid, pure vola- 
tile alkali dixssolvcd in water, solution of prussiate of 



C 141 ] 

potash and Iron, succinate of ammonia, soap lye, or 
solution of potossa, solutions of carbonate of ammo- 
nia, of muriate of ammonia, of neutral carbonate of 
potash, and nitrate of ammoniac. 

In cases when the general nature of the soil of a 
field is to be ascertained, specimens of it should be 
taken from different places, two or three inches below 
the surface, and examined as to the similarity of their 
properties. It sometimes happens, that upon plains 
the whole of the upper stratum of the land is of the 
same kind, and in this case, one analysis will be suffi- 
cient J but in vallies, and near the beds of rivers, there 
are very great differences, and it now and then occurs 
that one part ©f a field is calcareous, and another 
part siliceous ; and in this case, and in analogous ca- 
ses, the portions different from each other should be 
separately submitted to experiment. 

Soils when collected, if they cannot be imme- 
diately examined, should be preserved in phials quite 
filled with them, and closed with ground glass stop- 
pers. 

The quantity of soil most convenient for a perfect 
analysis, is from two to four hundred grains. It 
should be collected in dry weather, and exposed to 
the atmosphere till it becomes dry to the touch. 

The specific gravity of a soil, or the relation of 
its weight to that of water, may be ascertained by in- 
troducing into a phial, which will contain a known 
quantity of water, equal volumes of water and of soil, 
and this may be easily done by pouring in water till it 
is half full, and then adding the soil till the fluid rises 



C 142 ] 

to the mouth ; the difference between the weight of 
the soil and that of the water, will give the result. 
Thus if the bottle contains four hundred grains of 
water, and gains two hundred grains when half filled 
with water and half with soil, the specific gravity of 
the soil will be 2, that is, it will be twice as heavy as 
water, and if it gained one hundred and sixty-five grains, 
its specific gravity would be 1825, water being 1000. 

It is of importance, that the specific gravity of a 
soil should be known, as it affords an indication of 
the quantity of animal and vegetable matter it con- 
tains ; these substances being always most abundant 
m the lighter soils. 

The other physical properties of soils should 
likewise be examined before the analysis is made, as 
they denote, to a certain extent, their composition, 
and serve as guides in directing the experiments. 
Thus siliceous soils are generally rough to the touch, 
and scratch glass when rubbed upon it j ferruginous 
soils are of a red or yellow colour ; and calcareous 
soils are soft. 

1. Soils, though as dry as they can be made by 
continued exposure to air, in all cases still contain a 
considerable quantity of water, which adheres with 
great obstinacy to the earths and animal and vegeta- 
ble matter, and can only be driven off from them by 
a considerable degree of heat. The first process of 
analysis is, to free the given weight of soil from as 
much of this water as possible, without in other res- 
pects, affecting its composition j and this may be done 
by berating it for ten or twelve minutes over an Ar- 



i: 143 ] 

gand's lamp, in a bason of porcelain, to a temperature 
equal to 300 Fahrenheit ; and if a thermometer is not 
used, the proper degree may be easily ascertained, by 
keeping a piece of wood in contact with the bottom of 
the dish ; as long as the colour of the wood remains 
unaltered, the heat is not too high ; but when the 
wood begins to be charred, the process must be stop- 
ped. A small quantity of water will perhaps remain 
in the soil even after this operation, but it always af- 
fords useful comparative results ; and if a higher 
temperature were employed, the vegetable or animal 
matter would undergo decomposition, and in conse- 
quence the experiment be wholly unsatisfactory. 

The loss of weight in the process should be care- 
fully noted, and when in four hundred grains of soil 
it reaches as high as 50, the soil may be considered 
as in the greatest degree absorbent, and retentive of 
water, and will generally be found to contain much 
vegetable or animal matter, or a large proportion of 
aluminous earth. When the loss is only from 20 to 
10, the land may be considered as only slightly absor- 
bent and retentive, and siliceous earth probably forms 
the greatest part of it. 

2. None of the loose stones, gravel, or large 
vegetable fibres should be divided from the pure soil 
till after the water is drawn ofFj for these bodies are 
themselves often highly absorbent and retentive, and 
in consequence influence the fertility of the land. The 
next process, however, after that of heating, should be 
their separation, which may be easily accomplished by 
the sieve, after the soil has been gently bruised in a 



C 144 j 

mortar. The weights of the vegetable fibres or wood, 
and of the gravel and stones should be separately 
noted down, and the nature of the last ascertained ; 
if calcereous, they will effervesce with acids ; if sili- 
ceous, they will be sufficiently hard to scratch glass ; 
and if of the common aluminous class of stones, they 
will be soft, easily cut with a knife, and incapable of 
effervescing with acids. 

3. The greater number of soils, besides gravel 
and stones, contain larger or smaller proportions of 
sand of different degrees of fineness ; and it is a neces- 
sary operation, the next in the process of analysis, to 
detach them from the parts in a state of more minute 
division, such as clay, loam, marie, vegetable and ani- 
mal matter, and the matter soluble in water. This 
may be effected in a way sufficiently accurate, by boil- 
ing the soil in three or four times its weight of water ; 
and when the texture of the soil is broken down, and 
the water cool ; by agitating the parts together, and 
then suffering them to rest. In this case, the coarse 
sand will generally separate in a minute, and the finer 
in two or three minutes, whilst the highly divided earthy, 
animal, or vegetable matter will remain in a state of me- 
chanical supension for a much longer time ; so that by 
pouring the water from the bottom of the vessel, after 
one, two or three minutes, the sand will be principally 
separated from the other substances, which, with the 
water containing them, must be poured into a filtre, 
and after the water has passed through, collected, 
dried, and weighed. The sand must likewise be 
weighed, and the respective quantities noted down. 



C 14^ 5 

The water of lixiviation must be preserved, as it will 
be found to contain the saline and soluble animal or 
vegetable matters, if any exist in the soil. 

4. By the process of washing and filtration, the 
soil is separated into two portions, the most important 
of which is generally the finely divided matter. A 
minute analysis of the sand is seldom or never neces- 
sary, and its nature may be detected in the same man- 
ner as that of the stones or gravel. It is always either 
siliceous sand, or calcareous sand, or a mixture of 
both. If it consist wholly of carbonate of lime, it will 
be rapidly soluble in muriatic acid, with effervescence; 
but if it consist partly of this substance, and partly of 
siliceous matter, the respective quantities may be as- 
certained by weighing the residuum after the action of 
the acid, which must be applied till the mixture has 
acquired a sour taste, and has ceased to effervesce. 
This residuum is the siliceous part: it must be washed, 
dried, and heated strongly in a crucible; the difference 
between the weight of it and the weight of the whole, 
indicates the proportion of calcareous sand. 

5. The finely divided matter of the soil is usually 
very compound in its nature; it sometimes contains all 
the four primitive earths of soils, as well as animal and 
vegetable matter; and to ascertain the proportions of 
these with tolerable accuracy, is the most difficult part 
of the subject. 

The first process to be performed, in this part of 
the analysis, is the exposure of the fine matter of the 
soil to the action of muriatic acid. This substance 
should be poured upon the earthy matter in an eva-. 

u 



[ 146 ] 

porating bason, in a quantity equal to twice the weight 
of the earthy matter; but diluted with double its volume 
of water. The mixture should be often stirred, and 
suffered to remain for an hour, or an hour and a half, 
before it is examined. 

If any carbonate of lime or of magnesia exist in 
the soil, they will have been dissolved in this time by 
the acid, which sometimes takes up likewise a little 
oxide of iron; but very seldom any alumina. 

The fluid should be passed through a filtre; the 
solid matter collected, washed with rain water, dried 
at a moderate heat, and weighed. Its loss will denote 
the quantity of solid matter taken up. The washings 
must be added to the solution, which if not sour to the 
taste, must be made so by the addition of fresh acid, 
when a little solution of prussiate of potassa and iron 
must be mixed with the whole. If a blue precipitate 
occurs, it denotes the presence of oxide of iron, and 
the solution of the prussiate must be dropped in till 
no farther effect is produced. To ascertain its quan- 
tity, it must be collected in the same manner as other 
solid precipitates, and heated red; the result is oxide 
of iron, which may be mixed with a little oxide of 
manganesum. 

Into the fluid freed from oxide of iron, a solu- 
tion of neutralized carbonate of potash must be pour- 
ed till all effervescence ceases in it, and till its taste and 
smell indicate a considerable excess of alkaline salt. 

The precipitate that falls down is carbonate of 
lime; it must be collected on the filtre, and dried at a 
heat below that of redness. 



The remaining fluid must be boiled for a quarter 
of an hour, when the magnesia, if any exist, will be 
precipitated from it, combined with carbonic acid, and 
its quantity is to be ascertained in the same manner as 
that of the carbonate of lime. 

If any minute proportion of alumina should, 
from peculiar circumstances, be dissolved by the acid, 
it will be found in the precipitate with the carbonate of 
lime, and it may be separated from it by boiling it for 
a few minutes with soap lye, suflicient to cover the 
solid matter; this substance dissolves alumina, with- 
out acting upon carbonate of lime. 

Should the finely divided soil be sufficiently cal- 
careous to effervesce very strongly with acids, a very 
simple method may be adopted for ascertaining the 
quantity of carbonate of lime, and one sufficiently ac- 
curate in all common cases. 

Carbonate of lime, in all its states, contains a de- 
terminate proportion of carbonic acid, /. e. nearly 43 
per cent, so that when the quantity of this elastic fluid 
given out by any soil during the solution of its calcare- 
ous matter in an acid is known, either in weight or 
measure, the quantity of carbonate of lime may be 
easily discovered. 

When the process by diminution of weight is 
employed, two parts of the acid and one part of the 
matter of the soil must be weighed in two separate bot- 
tles, and very slowly mixed together till the efferves- 
cence ceases; the difference between their weight be- 
fore and after the experiment, denotes the quantity 
of carbonic carbonic acid lost; for every four grains 



[ 148 ] ^ 

and a quarter of which, ten grains of carbonate of 
lime must be estimated. 

The best method of collecting the carbonic acid, 
so as to discover its volume, is by a peculiar pneumat- 
ic, apparatus * in which its bulk may be measured by 
the quantity of water it dissolves. 

6. After the calcareous parts of the soil has been 
acted upon by muriatic acid, the next process is to as- 
certain the quantity of finely divided insoluble animal 
and vegetable matter that it contains. 

This may be done with sufficient precision, by 
strongly igniting it in a crucible over a common fire 
till no blackness remains in the mass. It should be 
often stirred with a metallic rod, so as to expose new 
surfaces continually to the air; the loss of weight that 
it undergoes denotes the quantity of the substance 
that it contains destructible by fire and air. 

It is not possible, without very refined and diffi- 
cult experiments, to ascertain whether this substance 



•Fig. IS. A, B, C, D, represent the different parts of this apparatus-. A. Repre- 
sents the bottlefor receiving the soil. B, the bottle containing the acid, furnished 
with a stop-cock. C. the tube connected with a flaccid bladder. D. The graduated 
msasure. E, The bottle for containing the bladder. When this instrument is used 
a given quantity of soil is introduced into A. Bis filled with muriatic aifid^ diluted, 
with an equal quantity of water; and the stop-cock being closed, is connected with 
she upper orifice of A, which is ground to receive it. The tube D is introduced 
into the lower orifice of A, and the bladder connected with it placed in iis flaccid 
state into E, which is filled with water. The graduated measure is placed under the 
tube of E. When the slop-cotk of B is turned, the acid flows into A, and acts 
upon the soil; the elastic Suid generated passes through C into the bladder, and 
displaces a quantity of water in E, equal to it in bulk, and this water flows through 
the tube into the graduated measure: and gives by its volume the indication of 
the proportion of carbonic acid disengaged from the soil; for every ounce measure 
of wlii:h tffo grains of carbonate of lime mav be estimated. 



p. 148 




[ 149 ] 

is wholly animal or vegetable matter, or a mixture of 
both. When the sniell emitted during the incinera- 
tion is similar to that of burnt feathers, it is a certain 
indication of some substance either animal or analo- 
gous to animal matter j and a copious blue flame at 
the time of ignition, almost always denotes a consi- 
derable proportion of vegetable matter. In cases 
when it is necessary that the experiment should be 
very quickly performed, the destruction of the decom- 
posable substances may be assisted by the agency of 
nitrate of ammoniac, which at the time of ignition may 
be thrown gradually upon the heated mass in the 
quantity of twenty grains for every hundred of residual 
soil. It accelerates the dissipation of the animal and 
vegetable matter, which it causes to be converted into 
elastic fluids ; and it is itself at the same time decom- 
posed and lost. 

7. The substances remaining after the destruc- 
tion of the vegetable and animal matter, are generally 
minute particles of earthy matter, containing usually 
alumina and silica, with combined oxide of iron or 
of majiganesum. 

To separate these from each other, the solid mat- 
ter should be boiled for two or three hours with sul- 
phuric acid, diluted with four times its weight of wa- 
ter ; the quantity of the acid should be regulated by 
the quantity of solid residuum to be acted on, allow- 
ing for every hundred grains, two drachms or one 
hundred and twenty grains of acid. 

The substance remaining after the action of the 
acid, may be considered as siliceous j and it must be 



C 150 ] 

separated and its weight ascertained, after washing 
and drying in the usual manner. 

The alumina and the oxide of iron and mangane- 
sum if any exist, are all dissolved by the sulphuric acid ; 
they may be separated by succinate of ammonia, ad- 
ded to excess ; which throws down the oxide of iron, 
and by soap lye, which will dissolve the alumina, but 
not the oxide of manganesum ; the weights of the 
oxides ascertained after they have been heated to red- 
ness will denote their quantities. 

Should any magnesia and lime have escaped so- 
lution in the muriatic acid, they will be found in the 
sulphuric acid ; this, however, is rarely the case ; but 
the process for detecting them, and ascertaining their 
quantities, is the same in both instances. 

The method of analysis by sulphuric acid, is suf- 
ficiently precise for all usual experiments ; but if very 
great accuracy be an object, dry carbonate of potassa 
must be employed as the agent, and the residuum of 
the incineration (6) must be heated red for a half hour, 
with four times its weight of this substance, in a cruci- 
ble of silver, or of well baked porcelain. The mass 
obtained must be dissolved in muriatic acid, and the 
solution evaporated till it is nearly solid ; distilled 
water must then be added, by which the oxide of iron 
and all the earths, except silica, will be dissolved in 
combination as muriates. The silica, after the usual 
|li*bcess of lixiviation, must be heated red ; the other 
substances may be separated in the same manner as 
from the muriatic and rvulohuric fiolntions. 



C 151 ] 

This process is the one usually employed by 
chemical philosophers for the analysis of stones, 

8. If any saline matter, or soluble vegetable or 
animal matter is suspected in the soil, it will be found 
in the water of lixiviation used for separating the 
sand. 

This water must be evaporated to dryness in a 
proper dish, at a heat below its boiling point. 

If the solid matter obtained is of a brown colour 
and inflammable, it may be considered as partly vege- 
table extract. If its smell, when exposed to heat, be 
like that of burnt feathers, it contains animal or albu- 
minous matter; if it be white, crystalline, and not 
destructible by heat, it may be considered as principal- 
ly saline matter ; the nature of which may be known 
by the tests described page 103. 

9. Should sulphate or phosphate of lime be sus- 
pected in the entire soil, the detection of them re- 
quires a particular process upon it. A given weight 
of it, for instance four hundred grains, must be heat- 
ed red for half an hour in a crucible, mixed with one- 
third of powdered charcoal. The mixture must be 
boiled for a quarter of an hour, in half a pint of water, 
and the fluid collected through the filtre, and exposed 
for some days to the atmosphere in an open vessel. 
If any notable quantity of sulphate of lime (gypsum) 
existed in the soil, a white precipitate will gradually 
form in the fluid, and the weight of it will indicate the 
proportion. 

Phosphate of lime, if any exist, may be separated 
from the soil after the process for gypsum. Muriatic 



L 152 j 

acid must be digested upon the soil, in quantity more 
than sufficient to saturate the soluble earths ; the 
solution must be evaporated, and water poured upon 
the solid matter. This fluid will dissolve the com- 
pounds of earths with the muriatic acid, and leave the 
phosphate of lime untouched. 

It would not fall within the limits assigned to this 
Lecture, to detail any processes for the detection of 
substances which may be accidentally mixed with the 
matters of soils. Other earths and metallic oxides 
are now and then found in them, but in quantities 
too minute to bear any relation to fertility or barren- 
ness, and the search for them would make analysis 
much more compli*;ated without rendering it more 
useful. 

10. When the examination of a soil is comple- 
ted, the products should be numerically arranged, 
and their quantities added together, and if they nearly 
equal the original quantity of soil, the analysis may be 
considered as accurate. It must, however, be noticed, 
that when phosphate or sulphate of lime are disco- 
vered by the independent process just described, (9, 
a correction must be made for the general process, by 
subtracting a sum equal to their weight from the 
quantity of carbonate of lime, obtained by precipita- 
tion from the muriatic acid. 

In arranging the products, the form should be in 
the order of the experiments by which they were pro- 
cured. 

Thiis, I obtained from 400 grains of a good sili- 
ceous sandy soil from a hop garden near Tunbridge, 
Kent, 



[ 153 ] 

grains. 
Of water of absorption - - - 19 

Of loose stones and gravel principally siliceous 53 

Of undecompounded vegetable fibres - 14 

Of fine siliceous sand - - - 212 

Of minutely divided matter separated by agitation 

and filtration, and consisting of 

Carbonate of lime - - - 19 
Carbonate of magnesia - - 3 

Matter destructible by heat, principally- 
vegetable - - - - 15 

Silica 21 

Alumina 13 

Oxide of iron - - - - 5 

Soluble matter, principally common 

salt and vegetable extract - 3 , 

Gypsum ---,.- 2 

— 81 

Amount of all the products 379 
Loss - . - - 21 
The loss in this analysis is not more than usually 
occurs, and it depends upon the impossibility of collec- 
ting the whole quantities of the different precipitates j 
and upon the presence of more moisture than is ac 
counted for in the water of absorption, and which is lost 
in the different processes. 

When the experimenter is become acquainted 
with the use of the different instruments, the proper- 
ties of the reagents, and the relations between the ex- 
ternal and chemical qualities of soils, he will seldom 
find it necessary to perform, in any one case, all the 

X 



C 154 ] 

processes that have been described. When his soil, 
for instance, contains no notable proportion of cal- 
careous matter, the action of the muriatic acid (7) 
may be omitted. In examining peat soils, he will 
principally have to attend to the operation by fire 
and air (8) ; and in the analysis of chalks and loams, 
he will often be able to omit the experiment by sul- 
phuric acid (9). 

In the first trials that are made by persons unac- 
quainted with chemistry, they must not expect much 
precision of result. Many difficulties will be met 
with : but in overcoming them, the most useful kind 
of practical knowledge will be obtained ; and nothing 
is so instructive in experimental science, as the detec- 
tion of mistakes- The correct analyst ought to be well 
grounded in general chemical information ; but perhaps 
there is no better mode of gaining it, than that of at- 
tempting original investigations. In pursuing his expe- 
riments, he will be continually obliged to learn the pro- 
perties of the substances he is employing or acting 
upon ; and his theoretical ideas will be more valuable 
in being connected with practical operations, and ac- 
quired for the purpose of discovery. 

Plants being possessed of no locomotive powers, 
can grow only in places where they are supplied with 
food ; and the soil is necessary to their existence, 
both as affording them nourishment, and enabling 
them to fix themselves in such a manner as to obey 
those mechanical laws by which their radicles are kept 
below the surface, and their leaves exposed to the free 
atmosphere. As the systems of roots, branches, and 



[ 155 J 

leaves are very different in different vegetables, so they ' 
flourish most in different soils : the plants that have 
bulbous roots require a looser and a lighter soil than 
such as have fibrous roots ; and the plants possessing 
only short fibrous radicles demand a firmer soil than 
such as have tap roots, or extensive lateral roots. 

A good turnip soil from Holkham, Norfolk, af- 
forded me 8 parts out of 9 siliceous sand j and the 
finely divided matter consisted 

Of carbonate of lime =. - - 63 

— silica » - - - - 15 

— alumina - - - - 11 

— oxide of iron - - - - 3 

— vegetable and saline matter - 5 

— moisture . - - - 3 

I found the soil taken from a field at Sheffield- 
place in Sussex, remarkable for producing flourishing 
oaks, to consist of six parts of sand, and one part 
of clay and finely divided matter. And one hundred 
parts of the entire soil submitted to analysis produced 



Silica - - . „ - 


parts, 
54! 


Alumina - - - - » 


28 


Carbonate of lime - . . 


3 


Oxide of iron - = - . 


5 


Decomposing vegetable matter 


4 


Moisture and loss - - _ 


3 


An excellent wheat soil from the neighbourhood 


of West Drayton, Middlesex, gave 3 parts 


in 5 of sill- 



[ 156 ] 

ceous sand; and the finely divided matter consiS' 

ted of 

Carbonate of lime - - - 28 

Silica 32 

Alumina 29 

Animal or vegetable matter and moisture 1 1 

Of these soils the last was by far the most, and 
the first the least, coherent in texture. In all cases 
the constituent parts of the soil which give tenacity and 
coherence are the finely divided matters ; and they 
possess the power of giving those qualities in the 
highest degree when they contain much alumina. A 
small quantity of finely divided matter is sufficient to 
fit a soil for the production of turnips and barley ; and 
I have seen a tolerable crop of turnips on a soil con- 
taining 1 1 parts out of 12 sand. A much greater pro- 
portion of sand, however, always produces absolute 
sterility. The soil of Bagshot heath, which is entire- 
ly devoid of vegetable covering, contains less than -is 
of finely divided matter. 400 parts of it, which had 
been heated red, afforded me 380 parts of coarse sili- 
ceous sand ; 9 parts of fine siliceous sand, and 1 1 
parts of impalpable matter which was a mixture of fer- 
ruginous clay, with carbonate of lime. Vegetable or 
animal matters, when finely divided, not only give co- 
herence, but likewise softness and penetrability ; but 
neither they nor any other part of the soil must be in 
too great proportion ; and a soil is unproductive if it 
consist entirely of impalpable matters. 

Pure alumina or silica, pure carbonate of lime, 
or carbonate of magnesia, are incapable of supporting 
healthy vegetation. 



C 157 ] 

No soil is fertile that contains as much as 19 parts 
out of 20 of any of the constituents that have been 
mentioned. 

It will be asked, are the pure earths in the soil 
merely active as mechanical or indirect chemical 
agents, or do they actually afford food to the plant? 
This is an important questionj and not difficult of sol- 
ution. 

The earths consist, as I have before stated, of 
metals united to oxygene; and these metals have not 
been decomposed; there is consequently no reason to 
suppose that the earths- are convertible into the ele- 
ments of organized compounds, into carbon, hydro- 
gene, and azote. 

Plants have been made to grow in given quanti- 
ties of earth. They consume very small portions only; 
and what is lost may be accounted for by the quantities 
found in their ashes; that is to say, it has not been 
converted into any new products. 

The carbonic acid united to lime or magnesia, if 
any stronger acid happens to be formed in the soil 
during the fermentation of vegetable matter which will 
disengage it from the earths, may be decomposed: 
but the earths themselves cannot be supposed convert- 
ible into other substances, by any process taking place 
in the soil. 

In all cases the ashes of plants contain some of 
the earths of the soil in which they grow; but these 
earths, as may be seen from the table of the ashes af- 
forded by different plants given in the last Lecture, 
never equal more than to of the Weight of the plant 
consumed. 



C, 158 ] 

If they be considered as necessary to the vegeta- 
ble, it is as giving hardness and firmness to its organi- 
zation. Thus, it has been mentioned that wheat, oats, 
and many of the hollow grasses, have an epidermis 
principally of siliceous earth; the use of which seems 
to be to strengthen them, and defend them from the 
attacks of insects and parasitical plants. 

Many soils are popularly distinguished as cold; 
and the distinction, though at first view it may appear 
to be founded on prejudice, is really just. 

Some soils are much more heated by the rays of 
the sun, all other circumstances being equal, than 
others; and soils brought to the same degree of heat 
cool in different times, i. e. some cool much faster 
than others. 

This property has been very little attended to in 
a philosophical point of view; yet it is of the highest 
importance in agriculture. In general, soils that con- 
sist principally of a stiff white clay are difficultly heated j 
and being usually very moist, they retain their heat 
only for a short time. Chalks are similar in one res- 
pect, that they are difficultly heated; but being drier 
they retain their heat longer, less being consumed in 
causing the evaporation of their moisture. 

A black soil, containing much soft vegetable mat- 
ter, is most heated by the sun and air; and the col- 
oured soils, and the soils containing much carbonace- 
ous matter, or ferruginous matter, exposed under 
equal circumstances to sun, acquire a much higher 
temperature than pale-coloured soils. 



C 159 3 

When soils are perfectly dry, those that most 
readily bec®me heated by the solar rays likewise cool 
most rapidly; but I have ascertained by experiment, that 
the darkest coloured dry soil (that which contains 
abundance of animal or vegetable matter; substances 
which most facilitate the diminution of temperature,) 
when heated to the same degree, provided it be with- 
in the common limits of the effect of solar heat, will 
cool more slowly than a wet pale soil, entirely com- 
posed of earthy matter. 

I found that a rich black mould, which contained 
nearly i. of vegetable matter, had its temperature in- 
creased in an hour from 65° to 88° by exposure to 
sunshine; whilst a chalk soil was heated only to 69° 
under the same circumstances. But the mould re- 
moved into the shade, where the temperature was 62°, 
lost, in half an hour, 15°; whereas the chalk, under 
the same circumstances, had lost only 4°. 

A brown fertile soil, and a cold barren clay were 
each artificially heated to 88°, having been previously 
dried: they were then exposed to a temperature of 57°; 
in half an hour the dark soil was found to have lost 9° 
of heat; the clay had lost only 6°. An equal portion 
of the clay containing moisture, after being heated to 
88°, was exposed in a temperature of 55°; in less than 
a quarter of an hour it was found to have gained the 
temperature of the room. The soils in all these ex- 
periments were placed in small tin plate trays two 
inches square, and half an inch in depth; and the tem- 
perature ascertained by a delicate thermometer. 

Nothing can be more evident, than that the 



C 160 ] 

genial heat of the soil, particularly in spring, must be 
of the highest importance to the rising plant. And 
when the leaves are fully developed, the ground is 
shaded; and any injurious influence, which in the sum- 
mer might be expected from too great a heat, entirely 
prevented: so that the temperature of the surface,, 
when bare and exposed to the rays of the sun, affords 
at least one indication of the degrees of its fertility; and 
the thermometer may be sometimes a useful instru- 
ment to the purchaser or improver of lands. 

The moisture in the soil influences its tempera- 
ture; and the manner in which it is distributed through, 
or combined with, the earthy materials, is of great 
importance in relation to the nutriment of the plant. 
If water is too strongly attracted by the earths, it will 
not be absorbed by the roots of the plants; if it is in 
too great quantity, or too loosely united to them, it 
tends to injure or destroy the fibrous parts of the 
roots. 

There are two states in which water seems to 
exist in the earths, and in animal and vegetable substan- 
ces: in the first state it is united by chemical, in the 
other by cohesive attraction. 

If pure solution of ammonia or potassa be poured 
into a solution of alum, alumina falls down combined 
with water; and the water dried by exposure to air will 
afford more than half its weight of water by distilla- 
tion; in this instance the water is united by chemical 
attraction. The moisture which wood, or muscular 
fibre, or gum, that have been heated to 212% afford 
bv distillation at a red heat, is likewise water, the ele- 



[ 161 ] 

ments of which were united in the substance by che- 
mical combination. 

When pipe-clay dried at the temperature of the 
atmosphere is brought in contact with water, the fluid 
is rapidly absorbed ; this is owing to cohesive attrac- 
tion. Soils in general, vegetable, and animal sub- 
stances, that have been dried at a heat below that of 
boiling water, increase in weight by exposure to air, 
owing to their absorbing water existing in the state of 
vapour in the air, in consequence of cohesive attrac- 
tion. 

The water chemically combined amongst the ele- 
ments of soils, unless in the case of the decomposition 
of animal or vegetable substances, cannot be absorbed 
by the roots of plants ; but that adhering to the parts 
of the soil is in constant use in vegetation. Indeed 
there are few mixtures of the earths found in soils, 
that contain any chemically combined water ; water 
is expelled from the earths by most substances that 
combine with them. Thus, if a combination of lime 
and water be exposed to carbonic acid, the carbonic 
acid. takes the place of water ; and compounds of alu- 
mina and silica, or other compounds of the earths, do 
not chemically unite with water : and soils, as it has 
been stated, are formed either by earthy carbonates, 
or compounds of the pure earths and metallic oxides^ 

When saline substances exist in soils, they may 
be united to water both chemically and mechanically ; 
but they are always in too small a quantity to influence 
materially th^ relations of the soil to water. 



[ 162 ] 

The power of the soil to absorb water by cohe- 
sive attraction, depends in great measure upon the 
state of division of its parts ; the more divided they 
are, the greater is their absorbent power. The differ- 
ent constituent parts of soils likewise appear to act, 
even by cohesive attraction, with different degrees of 
energy. Thus vegetable substances seem to be more 
absorbent than animal substances ; animal substances 
more so than compounds of alumina and silica ; and 
compounds of alumina and silica more absorbent than 
corbonates of lime and magnesia : these differences 
may, however, possibly depend upon the differences 
in their state of division, and upon the surface ex- 
posed. 

The po\\er of soils to absorb water from air, is 
much connected with fertility. When this power is 
great, the plant is supplied with moisture in dry sea- 
sons ; and the effect of evaporation in the day is coun- 
teracted by the absorption of aqueous vapour from 
the atmosphere, by the interior parts of the soil during 
the day, and by both the exterior and interior during 
night. 

The stiff clays approaching to pipe-clays in their 
nature, which take up the greatest quantity of water 
when it is poured upon them in a fluid form, are nor 
the soils which absorb most moisture from the atmos- 
phere in dry weather. They cake, and present only a 
small surface to the air ; and the vegetation on them 
is generally burnt up almost as readily as on sands. 

The soils that are most efficient in supplying the 
plant with water by atmospheric absorption, are those 



t 165 3 

in which there is a due mixture of sand, finely divided 
clay, and carbonate of lime, with some animal or ve- 
getable matter ; and which are so loose and light as 
to be freely permeable to the atmosphere. With res- 
pect to this quality, carbonate of lime and animal and. 
vegetable matter are of great use in soils ; they give 
absorbent power to the soil without giving it likewise 
tenacity : sand, which also destroys tenacity, on the 
contrary, gives little absorbent power. 

I have compared the absorbent powers of many 
soils with respect to atmospheric moisture, and I have 
always found it greatest in the most fertile soils : so 
that it affords one method of judging of the produc- 
tiveness of land. 

1000 parts of a celebrated soil from Ormiston, 
in East Lothian, which contained more than half its 
weight of finely divided matter, of which 11 parts 
were carbonate of lime, and 9 parts vegetable matter, 
when dried at 21 2°, gained in an hour by exposure to 
air saturated with moisture, at temperature 62°, 18 
grains. 

1000 parts of a very fertile soil from the banks 
of the river Parret, in Somersetshire, under the same 
circumstances, gained 16 grains. 

1000 parts of a soil from Mersea, in Essex, 
worth 45 shillings an acre, gained 13 grains. 

1000 grains of a fine sand from Essex, worth 
28 shillings an acre, gained 1 1 grains. 

1000 of a coarse sand worth 15 shillings an acre, 

gained only 8 grains. 

1000 of the soil of Bagr.hot-heath gained only S 
grains. 



[ 164 ] 

Water, and the decomposing animal and vegeta- 
ble matter existing in the soil, constitute the true 
nourishment of plants ; and as the earthy parts of the 
soil are useful in retaining water, so as to supply it 
in the proper proportions to the roots of the vegeta- 
bles, so they are likewise efficacious in producing the 
proper distribution of the animal or vegetable matter ; 
when equally mixed with it they prevent it from de- 
composing too rapidly ; and by their means the solu- 
ble parts are supplied in proper proportions. 

Besides this agency, which may be considered as 
mechanical, there is another agency between soils and 
organizable matters, which may be regarded as che- 
mical in its nature. The earths, and even the earthy 
carbonates, have a certain degree of chemical attrac- 
tion for many of the principles of vegetable and ani- 
mal substances. This is easily exemplified in the in- 
stance of alumina and oil j if an acid solution of alu- 
mina be mixed with a solution of soap, which consists 
of oily matter and potassa ; the oil and the alumina 
will unite and form a white powder, which will sink 
to the bottom of the fluid. 

The extract from decomposing vegetable matter 
when boiled with pipe-clay or chalk, forms a combina- 
tion by which the vegetable matter is rendered more 
difficult of decomposition and of solution. Pure silica 
and siliceous sands have little action of this kind ; and 
the soils which contain the most alumina and carbon- 
ate of lime, are these which act with the greatest che- 
mical energy in preserving manures. Such soils 
merit the appellation which is commonly given to them 



[ 165 2 

of rich soils ; for the vegetable nourishment is long 
preserved in them, unless taken up by the organs of 
plants. Siliceous sands, on the contrary, deserve the 
term hungry, which is commonly applied to them ; for 
the vegetable and animal matters they contain not be- 
ing attracted by the earthy constituent parts of the 
soil, are more liable to be decomposed by the action of 
the atmosphere, or carried off from them by water. 

In most of the black and brown rich vegetable 
moulds, the earths seem to be in combination with a 
peculiar extractive matter, afforded during the decom- 
position of vegetables : this is slowly taken up, or at- 
tracted from the earths by water, and appears to con- 
stitute a prime cause of the fertility of the soil. 

The standard of fertility of soils for different 
plants must vary with the climate ; and must be parti- 
cularly influenced by the quantity of rain. 

The power of soils to absorb moisture ought to^ 
be much greater in warm or dry counties, than in cold 
and moist ones ; and the quantity of clay, or vegeta- 
ble or animal matter they contain greater. Soils also 
on declivities ought to be more absorbent than in 
plains or in the bottom of vallies. Their productive- 
ness likewise is influenced by the nature of the sub- 
soil or the stratum on which they rest. 

When soils are immediately situated upon a bed 
of rock or stone, they are much sooner rendered dry 
by evaporation, than where the subsoil is of clay or 
marie ; and a prime cause of the great fertility of the 
land in the moist climate of Ireland, is the proximity 
of the rocky strata to the soil. 



t 166 ] 

A clayey subsoil will sometimes be of material 
advantage to a sandy soil; and in this case it will re- 
tain moisture in such a manner as to be capable of 
supplying that lost by the earth above, inconsequence 
of evaporation, or the consumption of it by plants. 

A sandy, or gravelly subsoil, often corrects the 
imperfections of too great a degree of absorbent power 
in the true soil. 

In calcareous countries, where the surface is a 
species of marie, the soil is often found only a few 
inches above the limestone; and its fertility is not im- 
paired by the proximity of the rock; though in a less 
absorbent soil, this situation would occasion barren- 
ness; and the sandstone and limestone hills in Derby- 
shire and North Wales, may be easily distinguished at 
a distance in summer by the different tints of the ve- 
getation. The grass on the sandstone hills usually 
appears brown and burnt up; that on the limestone 
hills, flourishing and green. 

In devoting the different parts of an estate to the 
necessary crops, it is perfectly evident from what has 
been said, that no general principle can be laid down, 
except when all the circumstances of the nature, com- 
position, and situation of the soil and subsoil are 
known. 

The methods of cultivation likewise must be dif- 
ferent for different soils. The same practice which will 
be excellent in one case may be destructive in another. 

Deep ploughing may be a very profitable practice 
in a rich thick soil; and in a fertile shallow soil, situa- 
ted upon cold clay or sandy subsoil, it may be ex- 
tremely prejudicial. 



C 167 3 

In a moist climate where the quantity of rain that 
falls annually equals from 40 to 60 inches, as in Lan- 
cashire, Cornwall, and some parts of Ireland, a silice- 
ous sandy soil is much more productive than in dry 
districts; and in such situations, wheat and beans will 
require a less coherent and absorbent soil than in 
drier situations; and plants having bulbous roots, will 
flourish in a soil containing as much as 14 parts out 
of 15 of sand. 

Even the exhausting powers of crops will be in- 
fluenced by like circumstances. In cases where plants 
cannot absorb sufficient moisture, they must take up 
more manure. And in Ireland, Cornwall, and the 
western Highlands of Scotland, corn will exhaust less 
than in dry inland situations. Oats, particularly in 
dry climates, are impoverishing in a much higher de- 
gree than in moist ones. 

Soils appear to have been originally produced in 
consequence of the decomposition of rocks and strata. 
It often happens that soils are found in an unaltered 
state upon the rocks from which they were derivedo 
It is easy to form an idea of the manner in which 
rocks are converted into soils, by referring to the in- 
stance of soft granite^ or procelain granite. This sub- 
stance consists of three ingredients, quartz, feldspar, 
and mica. The quartz is almost pure siliceous earth, 
in a crystalline form. The feldspar and mica are very 
compounded substances; both contam silica, alumina, 
and oxide of iron; in the feldspar there is usually 
lime and potassa; in the mica, lime and magnesia. 



C 168 3 

When a granitic rock of this kind has been long 
exposed to the influence of air and water, the lime 
and the potassa contained in its constituent parts are 
acted upon by water or carbonic acid; and the oxide 
of iron, which is ahnost always in its least oxided state, 
tends to combine with more oxygene; the consequence 
is, that the feldspar decomposes, and likewise the 
mica; but the first the most rapidly. The feldspar, 
which is as it were the cement of the stone, forms a 
fine clay: the mica partially decomposed mixes with 
it as sand; and the undecomposed quartz appears as 
gravel, or sand of different degrees of fineness. 

As soon as the smallest layer of earth is formed on 
the surface of a rock, the seeds of lichens, mosses, and 
other imperfect vegetables which are constantly float- 
ing in the atmosphere, and which have made it their 
resting place, begin to vegetate; their death, decompo^ 
sition, and decay afford a certain quantity of organi- 
zable matter, which mixes with the earthy materials of 
the rock; in this improved soil more perfect plants are 
capable of subsisting; these in their turn absorb nour- 
ishment from water and the atmosphere; and after per- 
ishing afford new materials to those already provided: 
the decomposition of the rock still continues; and at 
length by such slow and gradual processes, a soil is 
formed in which even forest trees can fix their roots, 
and which is fitted to reward the labours of the culti- 
vator. 

In instances where successive generations of vege- 
tables have grown upon a soil, unless part of their pro- 
duce has been carried off by man, or consumed by 



i 169 ] 

animals, the vegetable matter increases in such a pro- 
portion, that the soil approaches to a peat in its na- 
ture J and if in a situation where it can receive water 
from a higher district, it becomes spongy, and per- 
meated with that fluid and is gradually rendered in- 
capable of supporting the nobler classes of vegetables. 

Many peat-mosses seem to have been formed by 
the destruction of forests, in consequence of the impru- 
dent use of the hatchet by the early cultivators of the 
country in which they exist : when the trees are fel- 
led in the out-skirts of a wood, those in the interior ex- 
posed to the influence of the winds ; and having been 
accustomed to shelter, become unhealthy, and 
die in their new situation ; and their leaves and 
branches gradually decomposing, produce a stratum 
of vegetable matter. In many of the great bogs in 
Ireland and Scotland, the larger trees that are fo,und. 
in the out-skirts of them, bear the marks of having 
been felled. In the interior, few entire trees are 
found ; and the cause is, probably, that they fell by 
gradual decay ; and that the fermentation and decom- 
position of the vegetable matter was most rapid where 
it was in the greatest quantity. 

Lakes and pools of water are some times filled 
up by the accumulation of the remains of acquatic 
plants ; and in this case a sort of spurious peat is 
formed. The fermentation in these cases, however, 
seems to be of a diff'erent kind. Much more gaseous 
matter is evolved j and the neighbourhood of moras- 
ses in which aquatic vegetables decompose, is usually 
aguish and unhealthy ; whilst that of the true peat, or 



[ i70 ] 

peat formed on soils originally dry, is always salu- 
brious. 

The earthy matter of peats is uniformly analo- 
gous to that of the stratum on which they repose ; the 
plants which have formed them must have derived 
the earths that they contained from this stratum. 
Thus in Wiltshire and Berkshire, where the stratum 
below the peat is chalk, calcareous earth abounds in 
the ashes, and very little alumina and silica. They 
likewise contain much oxide of iron and gypsum, both 
of which may be derived from the decomposition of 
the pyrites, so abundant in chalk. 

Different specimens of peat that I have burnt, 
from the granitic and schistose soils of different parts 
of these islands have always given ashes principally 
siliceous and aluminous and a specimen of peat from 
the county of Antrim, gave ashes which afforded very 
nearly the same constituents as the great basaltic stra- 
tum of the county. 

Poor and hungry soils, such as are produced 
from the decomposition of granitic and sandstone 
rocks, remain very often for ages with only a thin co- 
vering of vegetation. Soils from the decomposition 
of limestone, chalks, and basalts arc often clothed by 
nature with the perennial grasses ; and afiord, when 
ploughed up, a rich bed of vegetation for every species 
of cultivated plant. 

Rocks and strata from which soils have been de- 
rived, and those Which compose the more interior 
:;olid parts of the globe, arc arranged in a certain or- 
der j and as it often happens that strata very different 



C ni ] 

ill their nature are associated together, and that the 
strata immediately beneath the soil contain materials 
which may be of use for improving it, a general view 
of the nature and position of rocks and strata in na- 
ture, will not, I trust, be unacceptable to the scientific 
farmer. 

Rocks are generally divided by geologists into 

two grand divisions, distinguished by the names of 
prhitary and secondary. 

The primary rocks are composed of pure crystal- 
line matter, and contain no fragments of other rocks. 

The secondary rocks, or strata, consist only part- 
ly of crystalline matter j contain fragments of other 
rocks or strata ; often abound in the remains of vege- 
tables and marine animals ; and sometimes contain 
the remains of land animals. 

The primary rocks are generally arranged in 
large masses, or in layers vertical, or more or less 
inclined to the hon5ron. 

The secondary rocks are usually disposed in 
strata or layers, parallel, or nearly parallel to the 
horizon. 

The number of primary rocks which are com- 
monly observed in nature are eight. 

First, granite, which, as has been mentioned, is 
composed of quartz, feldspar, and mica ; when these 
bodies are arranged in regular layers in the rock, it is 
called gneis. 

Second, micaceous schistus, which is composed of 
quartz and mica arranged in layers, which are usually 
curvilineal. 



C 172 ] 

Third, sienite, which consists of the substance 
called hornblende and feldspar. 

Fourth, serpentine, which is constituted by feld- 
spar and a body named resplendent hornblende ; and 
their separate crystals are often so small as to give 
the stone a uniform appearance : this rock abounds 
in veins of a substance called steatite, or soap rock. 

Fifth, porphyry, which constists of crystals of 
feldspar, embedded in the same material, but usually 
€>f a different colour. 

Sixth, granular marble, which consists entirely 
of crystals of carbonate of lime ; and which, when its 
colour is white, and texture fine, is the substance used 

by statuaries. 

Seventh, chlorite schist, which consists of chlo- 
rite, a green or grey substance somewhat analogous 
to mica and feldspar. 

Eight, quartzose rock, which is composed of 
quartz in a granular form, someti'mes united to small 
quantities of the crystalline elements, which have 
been mentioned as belonging to the other rocks. 

The secondary rocks are more numerous than 
the primary ; but twelve varieties include all that are 
usually found in these islands. 

First, grauwacke, which consists of fragments of 
quartz, or chlorite schist, embedded in a cement, 
principally composed of feldspar. 

Second, siliceous sandstone, which is composed of 
fine quartz or sand, united by a siliceous cement. 

Third, limestone, consisting of carbonate of lime, 
more compact in its texture than in the granular mar- 
ble ; and often abounding in marine exuvia. 



,% 



Fourth, aluminous schist, or shale, consisting of 
the decomposed materials of different rocks cemented 
by a small quantity of ferruginous or siliceous matter; 
and often containing the impressions of vegetables. 

Fifth, calcareous sandstone, which is calcareous 
sand, cemented by calcareous matter. 

Sixth, irone stone, formed of nearly the same ma- 
terials as aluminous schist, or shale ; but containing a 
much larger quantity of oxide or iron. 

Seventh, basalt or whinstone, which consists of 
feldspar and hornblende with materials derived from 
the decomposition of the primary rocks; the crystals 
are generally so small as to give the rock a homo- 
geneous appearance;- and it is often disposed in very 
regular columns, having usually five or six sides. 

Eighth, bituminous or common coal. 

Ninth, gypsum, the substance so well known by 
that name, which consists of sulphate of lime; and of- 
ten contains sand. 

Tenth, rock salt. 

Eleventh, chalk, which usually abounds in re- 
mains of marine animals, and contains horizontal 
layers of flints. 

Twelfth, plum-pudding stone, consisting of pebbles 
cemented by a ferruginous or siliceous cement. 

To describe more particularly the constituent 
parts of the different rocks and strata will be unneces- 
sary; at any time, indeed, details on this subject are 
useless, unless the specimens are examined by the 
^ye; and a close inspection and comparison of the dif- 



C n-i 3 

ferent species, will, in a short time, enable the most 
common observer to distinguish them. 

The highest mountains in these islands, and in- 
deed in the whole of the old continent, are constituted 
by granite; and this rock has likewise been found ar 
the greatest depths to which the industry of man has 
as yet been able to penetrate; micaceous schist is often 
found immediately upon granite; serpentine or marble 
upon micaceous schist: but the order in which jjae 
primary rocks are grouped together is various. Mar- 
ble and serpentine are usually found uppermost; but 
granite, though it seems to form the foundation of the 
rocky strata of the globe, is yet sometimes discovered 
above micaceous schist. 

The secondry rocks are always incumbent on the 
primary; the lowest of them is usually grauwacke: up- 
on this, Hmestone or sandstone is often found; coal 
generally occurs between sandstone or shale; basalt 
often exists above sandstone and limestone; rock salt 
almost always occurs associated with red sandstone 
and gypsum. Coal, basalt, sandstone, and limestone, 
are often arranged in different alternate layers, of no 
considerable thickness, so as to form a great extent of 
country. In a depth of less than 500 yards, 80 of 
these different alternate strata have been counted. 

The veins which afford metallic substances, are 
fissures more or less vertical, filled with a material 
different from the rock in which they exist. This 
material is almost always crystalline; and usually con- 
tyists of calcareous spar, fiuor spar, quartz, or heavy 
tpar, either separate or together. The metallic sub- 




5 S 



^ i 



.5 -2 =: 






C 175 2 

Stances are generally dispersed through, or confusedly 
mixed with these crystalline bodies. The veins in 
hard granite seldom afford much useful metalj but in 
the veins in soft granite, and in gneis, tin, copper, and 
lead are found. Copper and iron are the only metals 
usually found in the veins in serpentine. Micaceous 
schist, sienite, and granular marble, are seldom me- 
talliferous rocks. Lead, tin, copper, iron, and many 
other metals are found in the veins in chlorite schist. 
Grauwacke, when it contains few fragments and exists 
in large masses, is often aymetalliferous rock. The 
precious metals, likewise iron, lead, and antimony, are 
found in it; and sometimes it contains veins or masses 
of stone coal, or coal free from bitumen. Limestone 
is the great metalliferous rock of the secondary family; 
and lead and copper are the metals most usually found 
in it. No metallic veins have ever been found in 
shale, chalk, . or calcareous sandstone; and they are 
very rare in basalt and siliceous sandstone.* 

In cases where veins in rocks are exposed to the 
atmosphere, indications of the metals they contain may 
be often gained from their superficial appearance. 
Whenever fluor spar is found in a vein, there is al- 
ways strong reason to suspect that it is associated 
with metallic substances. A brown powder at the 
surface of a vein always indicates iron, and often tin; 
a pale yellow powder lead; and a green colour in a 
Tein denotes the presence of copper. 



* Fig. lo, Mill give a general ideaaf the appearance and arrangement of recks 
ana vein'. 



C 176 ] 

It may not be improper to give a general descrip- 
tion of the geological constitution of Great Britain and 
Ireland. Granite forms the great ridge of hills ex- 
tending from Land's End through Dartmoor hito De- 
vonshire. The highest rocky strata in Somersetshire 
are grauwacke and limestone. The Malvern hills are 
composed of granite, sienite, and porphyry. The 
highest mountains in Wales are chlorite schist, or 
grauwacke. Granite occurs at mount Sorrel in Lei- 
•cestershire. The great range of the mountains in 
Cumberland and Westmoreland, are porphyry, chlo- 
rite schist, and grauwacke; but granite is found at their 
western boundary. Throughout Scotland the most 
elevated rocks are granite, sienite, and micaceous 
schistus. No true secondary formations are found in 
South Britain, west of Dartmoor; and no basalt south 
of the Severn. The chalk district extends from the 
western part of Dorsetshire, to the eastern coast of 
Norfolk. The coal formations abound in the district 
between Glamorganshire and Derbyshire; and like- 
wise in the secondary strata of Yorkshire, Durham, 
Westmoreland, and Northumberland. Serpentine is 
found only in three places in Great Britain; near Cape 
Lizard in Cornwall, Portsoy in Aberdeenshire, and in 
Ayrshire. Black and grey granular marble is found 
near Padstow in Cornwall; and other coloured primary 
marbles exist in the neighbourhood of Plymouth. 
Coloured primary marbles are abundant in Scotland^ 
and white granular marble is found in the Isle of Sky, 
in Assynt, and on the banks of Loch Shin in Suther- 
land: the principle coal formations in Scotland are in 



C 177 ] 

-Dumbartonshire. Ayrshire, Fifeshire, and on 'the 
banks of the Brora in Sutherland. Secondary lime- 
stone and sandstone are found in most of the low 
countries north of the Mendip hills. 

In Ireland there are five great associations of pri- 
mary mountains ; the mountains of Morne in the 
county of Down ; the mountains of Donegal ; those 
of Mayo and Galway, those of Wicklow, and those 
of Kerry. The rocks composing the four first of 
these mountain chains are principally granite, gneis, 
sienite, micaceous schist, and porphyry. The moun- 
tains of Kerry are chiefly constituted by granular 
quartz, and chlorite schist. Coloured marble is found 
near Killarney; and white marble on the western coast 
of Donegal. 

Limestone and sandstone are the common secon- 
dary rocks found south of Dublin. In Sligo, Ros- 
common, and Leitrim, limestone, sandstone, shale, iron 
stone, and bituminous coal are found. The second- 
ary hills in these counties are of considerable eleva- 
tion ; and many of them have basaltic summits. The 
northern coast of Ireland is principally basalt ; this 
rock commonly reposes upon a white limestone, con- 
taining layers of flint, and the same fossils as chalk ; 
but it is considerably harder than that rock. There 
are some instances, in this district, in which columnar 
basalt is found above sandstone and shale, alternating 
with coal. The stone coal of Ireland is principally 
found in Kilkenny, associated with limestone and 
grauwacke, 

a2 



[ 178 3 

It is evident from what has been said concerning 
the production of soils from rocks, that there must be 
at least as many varieties of soils as there are species 
of rocks exposed at the surface of the earth ; in fact 
there are many more. Independent of the changes 
produced by cultivation and the exertions of human 
labour, the materials of strata have been mixed to- 
gether and transported from place to place by various 
great alterations that have taken piace in the system 
of our globe, and by the constant operation of water. 

To attempt to class soils with scientific accuracy, 
would be a vain labour ; tiie distinctions adopted by 
farmers are sufficient for the purposes of agriculture ; 
particularly if some degree of precision be adopted in 
the application of terms. The term sandy, for instance, 
should never be applied to any soil that does not con- 
tain at least | of sand ; sandy soils that effervesce with 
acids should be distinguished by the name of calcare- 
ous sandy soil, to distinguish them from those that 
are siliceous. The term clayey soil should not be 
applied to any land which contains less than | of im- 
palpable earthy matter, not considerably effervescing 
with acids : the word loam should be hmited to soils, 
containing at least one third of impalpable earthy mat- 
ter, copiously effervescing with acids. A soil to be 
considered as peaty, ought to contain at least one half 
of vegetable matter. 

In cases where the earthy part of a soil evidently 
consists of the decomposed matter of one particular 
rock, a name derived from the rock may with propriety 
be applied to it. Thus, if a fine red earth be found 



C 179 ] 

immediately above decomposing basalt, it may be de- 
nominated basaltic soil. If fragments of quartz and 
mica be found abundant in the materials of the soil, 
which is often the case, it may be denominated granule 
soil ; and the same principles may be applied to other 
like instances. 

In general, the soils, the materials of which are 
the most various and heterogenous, are those called 
alluvial, or which have been formed from the deposi- 
tions of rivers ; many of them are extremely fertile. 
I have examined some productive alluvial soils, which 
have been very different in their composition. The 
soil which has been mentioned page 163, as very pro- 
ductive, from the banks of the river Parret in Somer- 
setshire, afforded me eight parts of finely divided 
earthy matter, and one part of siliceous sand ; and an 
analysis of the finely divided matter gave the follow- 
ing results. 

360 parts of carbonate of lime, 
25 — — alumina, 

20 silica, 

8 oxide of iron. 

19 vegetable, animal, and saline matter. 

A rich soil from the neighbourhood of the Avon, 
in the valley of Evesham in Worcestershire, afforded 
me three fifths of fine sand, and two fifths of impalpa= 
ble matter ; the impalpable matter consisted of, 
35 Alumina, 
41 Silica, 

14 Carbonate of lime, 
3 Oxide of iron, 
7 Vegetable, animal, and saline matter. 



r ISO a 



A specimen of good soil from liviot-dale, afford 
ed five sixths of fine siliceous sand, and one sixth of 
impalpable matter ; which consisted of 

41 Alumina, 

42 Silica, 

4 Carbonate of lime, 

5 Oxide of iron, 

8 Vegetable, animal, and saline matter. 
A soil yielding excellent pasture from the valley 
of the Avon, near Salisbury, afforded one eleventh of 
coarse siliceous sand j and the finely divided matter 
consisted of 

7 Alumina, 
14 Silica, 

63 Carbonate of lime, 
2 Oxide of iron, 
14 Vegetable, animal, and saline matter. 
In all these instances the fertility seems to de- 
pend upon the state of division, and mixture of the 
earthy materials and the vegetable and animal matter ; 
and may be easily explained on the principles which I 
have endeavoured to elucidate in the preceding part 
of this Lecture. 

In ascertaining the composition of sterile soils 
with a view to their improvement, any particular 
ingredient which is the cause of their unproduc- 
tiveness, should be particularly attended to ; if possi- 
ble, they should be compared with fertile soils in the 
same neighbourhood, and in similar situations, as the 
difference of the composition may, in many cases, in- 
dicate the most proper methods of improvement. If 



i 



[ 181 ] 

on washing a sterile soil it is found to contain the salts 
of iron, or any acid matter, it may be ameliorated by 
the application of quick lime. A soil of good ap- 
parent texture from Lincolnshire, was put into my 
hands by Sir Joseph Banks as remarkable for steril- 
ity : on examining it, I found that it contained sul- 
phate of iron ; and I offered the obvious remedy of 
top dressing with lime, which converts the sulphate 
into a manure. If there be an excess of calcareous 
matter in the soil, it may be improved by the applica- 
tion of sand, or clay. Soils too abundant in sand are 
benefited by the use of clay, or marie, or vegetable 
matter. A field belonging to Sir Robert Vaughan at 
Nannau, Merionethshire, the soil of which was a light 
sand, was much burnt up in the summer of 1805 j I 
recommended to that gentleman the application of peat 
as a top dressing. The experiment was attended 
with immediate good effects ; and Sir Robert last year 
informed me, that the benefit was permanent. A de- 
ficiency of vegetable or animal matter must be sup- 
plied by manure. An excess of vegetable matter is 
to be removed by burning, or to be remedied by the 
application of earthy materials. The improvement of 
peats, or bogs, or marsh lands, must be preceded by 
draining ; stagnant water being injurious to all the 
nutritive classes of plants. Soft black peats, when 
drained, are often made productive by the mere appli- 
cation of sand or clay as a top dressing. When peats 
are acid, or contain ferruginous salts, calcareous mat- 
ter is absolutely necessary in bringing them into culti- 
vation. When thev abound in the branches and roots 



C 182 ] 

of trees, or when their surface entirely consists of liv- 
ing vegetables, the wood or the vegetables must either 
by carried off, or be destroyed by burning. In the 
last case their ashes afford earthy ingredients, fitted to 
improve the texture of the peat. 

The best natural soils are those of which the ma- 
terials have been derived from different strata; which 
have been minutely divided by air and water, and are in- 
timately blended together: and in improving soils arti- 
ficially, the farmer cannot do better than imitate the 
processes of nature. 

The materials necessary for the purpose are sel- 
dom far distant: coarse sand is often found immedi- 
ately on chalk; and beds of sand and gravel are 
common below clay. The labour of improving the 
texture or constitution of the soil, is repaid by a great 
permanent advantage; less manure is required, and its 
fertility insured: and capital laid out in this way secures 
for ever, the productiveness, and consequently the 
value of the land. 



183 



LECTURE V. 

On the nature and Coiistiut'wn of the Atmosphere; and 
its Influence on Vegetables, Of the Germination of 
Seeds. Of the Functions of Plants in their differ- 
etit Stages of Growth ; with a general view of the 
Progress of Vegetation. 

The constitution of the atmosphere has been al- 
ready generally referred to in the preceding Lectures. 
Water, carbonic acid gas, oxygene, and azote, have 
been mentioned as the principal substances compo- 
sing it; but more minute enquiries respecting their na- 
ture and agencies are necessary to afford correct 
views of the uses of the atmosphere in vegetation. 

On these enquiries I now propose to enter; the 
pursuit of them, I hope, will offer some objects of 
practical use in farming; and present some philosophi- 
cal illustrations of the manner in which plants are 
nourished; their organs unfolded, and their functions 
developed. 

If some of the salt called muriate of lime that 
has been just heated red be exposed to the air, even 
in the driest and coldest wheather, it will increase in 
weight and become moist; and in a certain time will be 
converted into a fluid. If put into a retort and heated, 
it will yield pure water; will gradually recover its 
pristine state; and, if heated red, its former weight: so 
that it is evident, that the water united to it was derived 



[; 184 ] 

from the air. And that it existed in the air in an invis- 
ible and elastic form, is proved by the circumstance, 
that if a given quantity of air be exposed to the 
salt; its volume and weight will diminish, provided the 
experiment be correctly made. 

The quantity of water which exists in air, as va- 
pour, varies with the temperature. In proportion as 
the weather is hotter, the quantity is greater. At 50** 
of Fahrenheit air contains about sV of its volume of 
vapour; and as the specific gravity of vapour is to that 
of air nearly as 10 to 15, this is about tV of its weight. 

At 100°, supposing that there is a free commu- 
nication with water, it contains about .'4 parts in vol- 
ume, or 2T in weight. It is the condensation of va- 
pour by diminution of the temperature of the atmos- 
phere, which is probably the principal cause of the 

formation of clouds, and of the deposition of dew, 
mist, snow, or hail. 

The power of different substances to absorb 
aqueous vapour from the atmosphere, by cohesive at- 
traction was discussed in the last Lecture. The leaves 
of living plants appear to act upon the vapour likewise 
in its elastic form, and to absorb it. Some vegetables 
increase in weight from this cause, when suspended in 
the atmosphere and unconnected with the soil; such 
are the houseleek, and different species of the aloe. 
In very intense heats, and when the soil is dry, the 
life of plants seems to be preserved by the absorbent 
power of their leaves: and it is a beautiful circumstance 
in the ceconomy of nature, that aqueous vapour is 
most abundant in the atmosphere when it is most need- 



[ 185 ] 

ed for the purposes of life ; and that when other 
sources of its supply are cut off, this is most copious. 

The compound nature of water has been referred 
lo. It may be proper to mention the experimental 
proofs of its decomposition into, and composition 
from, oxygene and hydrogene. 

If the metal called potassium be exposed in a 
glass tube to a small quantity of water, it will act upon 
it with great violence ; elastic fluid will be disengaged, 
which will be found to be hydrogene ; and the same ef- 
fects will be produced upon the potassium, as if it had 
absorbed a small quantity of oxygene ; and the hydro- 
gene disengaged, and the oxygene added to the potas- 
sium are in weight as 2 to 15 ; and if two in volume of 
hydrogene, and one in volume of oxygene, which have 
the weights of 2 and 15, be introduced into a close ves- 
sel, and an electrical spark passed through them, they 
will inflame and condense into 1 7 parts of pure water. 

It is evident from the statements given in the third 
Lecture, that water forms by far the greatest part of 
the sap of plants ; and that this substance, or its ele- 
ments, enters largely into the constitution of their or- 
gans and solid productions. 

Water is absolutely necessary to the oeconomy of 
vegetation in its elastic and fluid state ; and it is not 
devoid of use even in its solid form. Snow and ice 
are bad conductors of heat ; and when the ground is 
covered with snow, or the surface of the soil or of 
water is frozen, the roots or bulbs of the plants be- 
neath are protected by the congealed water from the 
influence of the atmosphere, the temperature of which 

b2 



[ 186 ] 

in northern winters is usually very much below the 
freezing point ; and this water becomes the first nour- 
ishment of the plant in early spring. The expansion 
of water during its congelation, at which time its 
volume increases ^29 ^^^ its contraction of bulk dur- 
ing a thaw, tend to pulverise the soil ; to separate its 
parts from each other, and to make it more permeable 
to the influence of the air. 

If a solution of lime in water be exposed to the 
air, a pellicle will speedily form upon it, and a solid 
matter will gradually fall to the bottom of the water, 
and in a certain time the water will become tasteless ; 
this is owing to the conbination of the lime, which 
was dissolved in the water, with carbonic acid gas 
which existed in the atmosphere, as may be proved 
by collecting the film and the solid matter, and ignit- 
ing them strongly in a little tube of platina or iron ; 
they will give off carbonic acid gas, and will become 
quicklime, which added to the same water, will again 
bring it to the state of lime water. 

The quantity of carbonic acid gas in the atmos- 
phere is very small. It is not easy to determine it 
with precision, and it must differ in different situa- 
-tions ; but where there is a free circulation of air, it 
is probably never more than sU, nor less than jh of 
the volume of air. Carbonic acid gas is nearly j hea- 
vier than the other elastic parts of the atmosphere iii 
their mixed state ; hence at first view it might be sup- 
posed that it would be most abundant in the lower 
regions of the atmosphere ; but unless it has been 
Immediately produced at the surface of the earth ill 



C 187 ] 

some chjinical process, this does not seem to be the 
case : elastic fluids of different specific gravities have 
a tendency to equable mixture by a species of attrac- 
tion, and the different parts of the atmosphere are 
constantly agitated and blended together by winds or 
other causes. De Saussure found lime water preci- 
pitated on Mount Blanc, the highest point of land in 
JEurope ; and carbonic acid gas has been always found 
apparently in due proportion, in the air brought down 
from great heights in the atmosphere by aerostatic 
adventurers. 

The experimental proofs of the composition of 
carbonic acid gas are very simple. If 13 grains of 
well burnt charcoal be inflamed by a burning-glass in 
J 00 cubical inches of oxygene gas, the charc®al will 
.'intirely disappear ; and provided the experiment be 
correctly made, all the oxygene except a few cubical 
inches, will be found converted into carbonic acid ; 
and what is very remarkable, the volume of the gas is 
not changed. On this last circumstance it is easy to 
found a correct estimation of the quantity of pure 
charcoal and oxygene in carbonic acid gas : the weight 
of 100 cubical inches of oxygene gas is to that of 100 
cubical inches of oxygene gas, as 47 to 34 : so that 
47 parts in weight of carbonic acid gas, must be 
composed of 34 parts of oxygene and 13 of charcoal, 
which correspond with the numbers given in the se- 
cond Lecture. 

Carbonic acid is easily decomposed by heating 
potassium in it ; the metal combines with the oxy- 
gene, and the charcoal is deposited in the form of a 
black powder. 



L 188 ] 

The principal consumption of the carbonic acid 
in the atmosphere, seems to be in affording nourish- 
ment to plants ; and some of them appear to be sup- 
plied with carbon chiefly from this source. 

Carbonic acid gas is formed during fermentation, 
combustion, putrefaction, respiration, and a number 
of operations taking place upon the surface of the 
earth ; and there is no other process known in nature 
by which it can be destroyed but by vegetation. 

After a given portion of air has been deprived of 
aqueous vapour and carbonic acid gas, it appears little 
altered in its properties ; it supports combustion and 
animal life. There are many modes of separating its 
principal constituents, oxygene and azote, from each 
other. A simple one is by burning phosphorus in a 
confined volume of air : this absorbs the oxygene and 
leaves the azote ; and 1 00 parts in volume of air, in 
which phosphorus has been burnt, yield 79 parts of 
azote J and by mixing this azote with 21 parts of 
fresh oxygene gas ^rtifically procured, k substance 
having the original characters of air is produced. To 
procure pure oxygene from air, quicksilver may be 
kept heated in it, at about 600'', till it becomes a<red 
powder ; this powder, when ignited, will be restored 
to the state of quicksilver by giving off oxygene. 

Oxygene is necessary to some functions of vege- 
tables ; but its great importance in nature is in its rela- 
tion to the ceconomy of animals. It is absolutely ne- 
cessary to their life. Atmospheric air taken into the 
lungs of animals, or passed in solution in water 
through the gills of fishes, loses oxygene j and for 



C 189 ] 

ihe oxygene lost, about an equal volume of carbonic 
acid appears. 

The effects of azote in vegetation are not distinct- 
ly known. As it is found in some of the products of 
vegetation, it may be absorbed by certain plants from 
the atmosphere. It prevents the action of oxygene from 
being too energetic, and serves as a medium in which 
the more essential parts of the air act; nor is this cir- 
i:umstance unconformable to the analogy of nature; for 
the elements most abundant on the solid surface of 
the globe, are not those which are the most essential 
to the existence of the living beings belonging to it. 

The action of the atmosphere on plants differs 
at different periods of their growth, and varies with 
the various stages of the developement and decay of 
their organs; some general idea of its influence may 
have been gained from circumstances already mention- 
ed: I shall now refer to it more particularly, and endea- 
vour to connect it with a general view of the progress 
of vegetation. 

If a healthy seed be moistened and exposed to 
iair at a temperature not below 45°, it soon germinates; 
it shoots forth a plume which rises upwards, and a 
radicle which descends. 

If the air be confined, it is found that in the pro- 
cess of germination the oxygene, or a part of it is ab- 
sorbed. The azote remains unaltered; no carbonic 
acid is taken away from the air, on the contrary some 
is added. 

Seeds are incapable of germinating, except when 
oxygene is present. In the exhausted receiver of the 



C 190 J 

air-pump, in pure azote, in pure carbonic acid, wiieu 
moistened they swell, but do not vegetate; and if kept 
in these gasses lose their living powers, and undergo 
putrefaction. 

If a seed be examined before germination, it will 
be found more or less insipid, at least not sweet; but 
after germination it is always sweet. Its coagulated 
mucilage, or starch, is converted into sugar in the pro- 
cess; a substance difficult of solution is changed into 
one easily soluble; and the sugar carried through the 
cells or vessels of the cotyledons, is the nourishment 
of the infant plant. It is easy to understand the nature 
of the change, by referring to the facts mentioned in 
the third Lecture; and the production of carbonic 
^cid renders probable the idea, that the principal che- 
mical difference between sugar and mucilage depends 
upon a slight differencein the proportions of their car« 
bon. 

The absorption of oxygene by the seed in germin- 
ation, has been compared to its absorption in produ- 
cing the evolution of foetal life in the egg; but this an- 
alogy is only remote. All animals, from the most to 
the least perfect classes, require a supply of oxygene.* 



• The impregnated eggs of insects, and even fishes, do not produce young oneE> 
unless they are supplied with -mv, that is, unless the fcetus can respire. I lis-' t 
0)undthat the eggs of moths did not produce larv.'e when confined in pure carbonic 
acid; and when they were exposed in common air, the oxygene partly disappeared) 
and carbonic acid was formed. The fi/u iii 'the egg or the spawn, gains its oxygene 
from the air dissolved in water; and those fishes that spawn in spring and summer 
1,1 stiii water, such as the pike, carp, perch, and bream, deposit their eggs upon 
.subaquatic vegetables, the leaves of which, in performing their healthy functions, 
s^jpply oxygene to the water. The fixh th^t snnwn iu winter such as the s.ilmor^ 



C J91 1 

From, the moment the heart begins to pulsate till it 
ceases to beat, the aeration of the blood is constant, 
and the function of respiration invariable; carbonic 
acid is given off in the process, but the chemical 
change produced in the blood is unknown; nor is there 
any reason to suppose the formation of any substance 
similar to sugar. In the production of a plant from a 
seed, some reservoir of nourishment is needed before 
the root can supply sap; and this reservoir is the coty- 
ledon in which it is stored up in an insoluble form, and 
protected if necessary during the winter, and rendered 
soluble by agents which are constantly present on the 
surface. The change of starch into sugar, connected 
with the absorption of oxygene, may be rather com- 
pared to a process of fermentation than to that of re- 
spiration; it is a change eifected upon unorganized 
matter, and can be artificially imitated; and in most of 
the chemical changes that occur when vegetable com- 
pounds aje exposed to air, oxygene is absorbed, and 
carbonic acid formed or evolved. 

It is evident, that in all cases of tillage the seeds 
should be sown so as to be fully exposed to the influ- 
ence of the air. And one cause of the unproductive- 
ness of cold clayey adhesive soils is, that the seed is 
coated with matter impermeable to air. 



and trout, seek spots where there is a constant supply of fresh water, as near the 
sources of streams as possible, and in the most rapid currents where alJ stagnatioa 
xs prevented, and where the water is saturated with air, to which it has been ev 
posed during its deposition from clouds. It is the instinct leading these fish to 
seek a supply of air for their eggs which carries them from seas, or lakes into the 
mountain country; which induces them to move agartist the stream, and to endt&l 
our to overleap weir':, miU-dams, and cataracts. 



C 192 3 

In sandy soils the earth is always sufficiently pen- 
etrable by the atmosphere; but in clayey soils there 
can scarcely be too great a mechanical division of 
parts in the process of tillage. Any seed not fully 
supplied with air, always produces a weak and diseas- 
ed plant. 

The process of malting, which has been already 
referred to, is merely a process in which germination 
is artificially produced; and in which the starch of the 
cotyledon is changed into sugar; which sugar is after- 
wards, by fermination, converted into spirit. 

It is very evident from the chemical principles of 
germination, that the process of malting should be 
carried on no farther than to produce the sprouting of 
the radicle, and should be checked as soon as this has 
made its distinct appearance. If it is pushed to such 
a degree as to occasion the perfect development of the 
radicle and the plume, a considerable quantity of sac- 
charine matter will have been consumed in producing 
their expansion, and there will be less spirit formed in 
fermentation, or produced in distillation. 

As this circumstance is of some importance, I 
made in October 1806, an experiment relating to it. 
I ascertained by the action of alcohol, the relative pro- 
portions of saccharine matter in two equal quantities 
of the same barley; in one of which the germination 
had proceeded so far as to occasion protrusion of the 
radicle to nearly a quarter of an inch beyond the grain 
in most of the specimens, and in the other of which it 
had been checked before the radicle was a line in 
length; the quantity of sugar afforded by the last was 
fo that in the first nearly as six to five. 



[ 193 ] 

The saccharine matter in the (Cotyledons at the 
time of their change into seed-leaves, renders them ex- 
ceedingly liable to the attacks of insects : this princi- 
ple is at once a nourishment of plants and animals, 
and the greatest ravages are committed upon crops in 
the lirst stage of their growth. 

The turnip fly, an insect of the colyoptera genus, 
fixes itself upon the seed-leaves of the turnip at the 
time that they are beginning to perform their func- 
tions ; and when the rough leaves of the plume are 
thrown forth, it is incapable of injuring the plant to 
any extent. 

Several methods have been proposed for destroy- 
ing the turnip fly, or for preventing it from injuring 
the crop. It has been proposed to sow radish-seed 
with the turnip-seed, on the idea that the insect is fon- 
der of the seed-leaves of the radish than those of the 
turnip J it is said that this plan has not been success- 
ful, and that the fly feeds indiscriminately on both. 

There are several chemical menstrua which ren- 
der the process of germination much more rapid, 
when the seeds have been steeped in them. As in 
these cases the seed-leaves are quickly produced, and 
more speedily perform theit functions, I proposed it 
as a subject of experiment to examine whether such 
menstrua might not be useful in raising the turnip 
more speedily to that state in which it would be se- 
cure from the fly ; but the result proved that the prac- 
tice was inadmissible ; for seeds so treated, though 
they germinated much quicker, did not produce 
healthy plants, and often died soon after sprouting. 

c 2 



[ 194 ] 

I steeped radish seeds in September 1807, for 12 
hours, in a solution of chlorine, and similar seeds in 
very diluted nitric acid, in very diluted sulphuric acid, 
in weak solution of oxysulphate of iron, and some in 
common water. The seeds in solutions of chlorine 
and oxysulphate of iron, threw out the germ in two 
days ; those in nitric acid in three days, in sulphuric 
acid in five, and those in water in seven days. But 
in the cases of premature germination, though the 
plume was very vigorous for a short time, yet it be- 
came at the end of a fortnight weak and sickly ; and 
at that period less vigorous in its growth than the 
sprouts which had been naturally developed, so that 
there can be scarcely any useful application of these 
experiments. Too rapid growth and premature de- 
cay seem invariably connected in organized struc- 
tures ; and it is only by following the slow operations 
of natural causes, that we are capable of making im- 
provements. 

There is a number of chemical substances which 
are very oiFensive and even deadly to insects, which 
do not injure, and some of which even assist vegeta- 
tion. Several of these mixtures have been tried with 
various success ; a mixture of sulphur and lime, 
which is very destructive to slugs, does not prevent 
the ravages of the fly on the young turnip crop. His 
Grace the Duke of Bedford, at my suggestion, was 
so good as to order the experiment to be tried on a 
considerable scale at Woburn farm : the mixture of 
lime and sulphur was strewed over one part of a field 
sown with turnips j nothing was applied to the other 



C 195 ] 

part, but both were attacked nearly In the same man- 
ner by the fly. 

Mixtures of soot and quicklime, and urine and 
quicklime, will probably be more efficacious. The 
volatile alkali given off by these mixtures is offensive 
to insects ; and they afford nourishment to the plant. 
Mr. T. A. Knight* Informs me, that he has tried 
the method by ammoniacal fumes with success j but 
more extensive trials are necessary to establish its gen- 



• Mr. Knight has been so good as to furnish me with the following note on 
this subject. 

" The experiment which I'tried the year before last, and last year, to pre- 
serve turnips from the fly, has not been sufficiently often repeated to enable me t» 
speak with any degree of decision ; and last year all my turnips succeeded per- 
fectly well. In consequence of your suggestion, when I had the pleasure to meet 
you some years ago at Holkham, that lime slaked with urine might possibly be 
found to kill, or drive off, the insects from a turnip crop, I tried that preparation 
in mixture with three parts of soot, which was put into a small barrel, with gim- 
blet holes round it, to permit a certain quantity of the composition, about four 
bushels 80 an acre, to pass out, and to fall into the drills with the turnip seeds. 
Whether it was by affording highly stimulating food to the plant, or giving some 
flavour which the flies did not like, I cannot tell ; but in the year 1811, the adjoin- 
ing rows were eaten away, and those to which the composition was applied, as 
above described, were scarcely at all touched* It is my intention in future to drill 
my crop in, first, with the composition on the top of the ridge ; and then to sow 
at least a pound of seed, broad-cast, over the whole ground. The expense of this 
win be very trifling, not more than 2s. per acre ; and the horse-hoe will instantly 
sweep away all the supernumeraries between the rows, should those escape the 
flies, to which however they will be chiefly attracted ; because it will always be 
found that those insects prefer turnips growing in poor, to those in rich ground. 
One advantage seems to be the acceleration given to the growth of the plants, 
by the highly stimulative effects of the food they instantly receive as soon as their 
growth commences, and long before their radicles have reached the dung. The 
directions abcive given apply only to turnips sewed upon ridges, with the manure 
unmediately under them ; and I am quite certain, that in all soils turnips should 
be thus cultivated. I'he close vicinity of the manure, and the consequent shore 
time required to carry the food into the leaf, and return the organizable matter to 
the roots, are, in my hypothesis, points of vast importance ; aad th» results in 
practice are correspondent." 



C 196 ] 

eral efficacy. It may, however, be safely adopted, for 
if it should fail in destroying the fly, it will at least be 
an useful manure to the land. 

Alter the roots and leaves of the infant plant are 
formed, the cells and tubes throughout its structure 
become filled with fluid, which is usually supplied from 
the soil, and the function of nourishment is perform- 
ed by the action of its organs upon the external ele- 
ments. The constituent parts of the air are subser- 
vient to this process ; but, as it might be expected, 
they act differently under different circumstances. 

When a growing plant, the roots of which are sup- 
plied with proper nourishment, is* exposed in the pre- 
sence of solar light to a given quantity of atmospheri- 
cal air, containing its due proportion of carbonic acid, 
the carbonic acid after a certain time is destroyed, and 
a certain quantity of oxygene is found in its place. If 
new quantities of carbonic acid gas be supplied, the 
same result occurs ; so that carbon is added to plants 
from the air by the process of vegetation in sunshine 5 
and oxygene is added to the atmosphere. 

This circumstance is proved by a number of ex- 
periments made by Drs. Priestley, Ingenhousz and 
Woodhouse, and M. T. dfe Saussure ; many of which 
I have repeated with similar results. The absorption 
of carbonic acid gas, and the production of oxygene 
are performed by the leaf ; and leaves recently separ- 
ated from the tree effect the change, when confined in 
portions of air containing carbonic acid ; and absorb 
carbonic acid and produce oxygene, even when im» 
mersed in water holding carbonic acid in solution. 



C 197 3 

The carbonic acid is probably absorbed by the 
fluids in the cells of the green or parenchymatous part 
of the leaf; and it is from this part that oxygene gas 
is produced during the presence of light. M. Senne- 
bier found that the leaf, from which the epidermis was 
stripped off, continued to produce oxygene when 
placed in water, containing carbonic acid gas, and the 
globules of air rose from the denuded parenchyma; 
and it is shewn both from the experiments of Senne- 
bier and Woodhouse, that the leaves most abundant 
in parenchymatous parts produce most oxygene in 
water impregnated with carbonic acid. 

Some few plants * will vegetate in an artificial at- 
mosphere, consisting principally of carbonic acid, and 
many will grow for some time in air, containing from 
one-half to one-third; but they ^re not so healthy as 
when supplied with smaller quantities of this elastic 

substance. 

Plants exposed to light have been found to pro- 
duce oxygene gas in an elastic medium and in wa- 
ter, containing no carbonic acid gas; but in quantities 
much smaller than when carbonic acid gas was pre- 
sent. 

In the dark no oxygene gas is produced by 
plants, whatever be the elastic medium to which they 
are exposed; and no carbonic acid absorbed. In most 
cases, on the contrary, oxygene gas, if it be present, is 
absorbed, and carbonic acid gas is produced. 



* I found the Arenaria teiiuifolia to produce oxygene in carbonic acid> which 
yi*i nearly pure. 



[ 19S J 

In the changes that take place in the composition 
of the organized parts, it is probable that saccharine 
compounds are principally formed during the absence 
of light; gnm, woody fibre, oils, and resins during 
its presence; and the evolution of carbonic acid gas, or 
its formation during the night, may be necessary to 
give greater solubility to certain compounds in the 
plant. I once suspected that all the carbonic acid gas 
produced by plants in the night, or in shade, might be 
owing to the decay of some part of the leaf, or epider- 
mis; but the recent experiments of Mr. D. Ellis, are 
opposed to this idea; and I found that a perfectly 
healthy plant of celery, placed in a given portion of air 
for a few hours'only, occasioned a production of car- 
bonic acid gas, and an absorption of oxygene. 

Some persons have supposed that plants exposed 
in the free atmosphere to the vicissitudes of sunshine 
and shade, light and darkness, consume more oxy- 
gene than they produce, and that their permanent agen- 
cy upon air is similar to that of animals; and this opin- 
ion is espoused by the writer on the subject 1 have 
just quoted, in his ingenious researches on vegetation. 
But all the experiments brought forwards in favour of 
this idea, and particularly his experiments, have been 
made under circumstances unfavourable to accuracy 
of result. The plants have been confined and suppli- 
ed with food in an unnatural manner; and the influ- 
ence of light upon them has been very much dimin* 
ished by the nature of the media through which it pas^ 3 
sed. Plants confined in hmited portions of atmos- 
pheric air soon become diseased; their leaves decay, 



and by their decomposition they rapidly destroy tlie 

oxygene of the air. In some of the early experiments 

^ of Dr. Priestley before he was acquainted with the 

''agency of light upon leaves, air that had supported 

I combustion and respiration, was found purified by the 

ij growth of plants when they were exposed in it for suc- 

I cessive days and nights ; and his experiments are the 

more unexceptionable, as the plants, in many of them, 

grew in their natural states ; and shoots, or branches 

from them, only where introduced through water into 

the confined atmosphere. 

I have made some few researches on this subject, 
and I shall describe their results. On the 12th of 
July, 1800, I place a turf four inches square, clothed 
with grass, principally meadow fox-tail, and white 
clover, in a porcelain dish, standing in a shallow tray 
filled with water j I then covered it with a jar of flint 
glass, containing 380 cubical inches of common air in 
its natural state. It was exposed in a garden, so as 
to be liable to the same changes with respect to light 
;as in the common air. On the 20th of July the results 
were examined. There was an increase of the volume 
of the gas, amounting to fifteen cubical inches : but the 
jCemperature had changed from 64** to 71° j and the 
{pressure of the atmosphere, which on the 12th had 
been equal to the support of 30.1 inches of mercury, 
!»vas now equal to that of 30.2. Some of the leaves of 
|:he white clover, and of the fox-tail were yellow, and 
•the whole appearance of the grass less healthy than 
ivhen it was first introduced. A cubical inch of the 
'^y agitated in lime-water, gave a slight turbidness to 



[ 200 ] 

the water ; and the absorption was not quite -h oi its 
volume. 10 parts of the residual gas exposed to a 
solution of green sulphate of iron, impregnated with 
nitrous gas, a substance which rapidly absorbs oxygene 
from air, occasioned a diminution to 80 parts. 00 
parts of the air of the garden occasioned a diminution 

to 79 parts. 

If the results of this experiment be calculated 
upon, it will appear that the air had been slightly: 
deteriorated by the action of the grasses. But the 
weather was unusually cloudy during the progress of 
the experiment ; the plants had not been supphed in a 
natural manner with carbonic acid gas ; and the quan*. 
tity formed during the night, and by the action of the 
faded leaves, must have been partly dissolved by the 
water ; and that this was actually the case, I proved 
by pouring lime-water into the water, when an imme- 
diate precipitation was occasioned. Ihe mcrease of 
azote I am incHned to attribute to common air disen- 
gaged from the water. 

The following experiment I consider as conduct- 
ed under circumstances more analogous to tliose exis- 
ting in nature. A turf four inches square, from an 
irrigated meadow, clothed with common meadow 
grass, meadow fox-tail grass, and vernal meadow grass, 
was placed in a porcelain dish, which swam onthe sur- 
face of water impregnated with carbonic acid gas. A 
vessel of thin flint glass, of the capacity of 230 cubi- 
cal inches, having a funnel furnished with stop-cock 
inserted in the top, was made to cover the grass ; and 
the apparatus was exposed in an open place ; a small 



[ 201 ] 

quantity of water was daily supplied to the grass by 
means of the stop-cock.* Every day likewise a certain 
quantity of water was removed by a siphon, and water 
staturated with carbonic acid gas supplied in its place ; 
so that it may be presumed, that a small quantity of 
carbonic acid gas was constantly present in the re- 
ceiver. On the 7th of July, 1807, the first day of 
the experiment, the weather was cloudy in the morn- 
ing, but fine in the afternoon ; the thermometer at 
67, the barometer 30.2 : towards the evening of this 
day a slight increase of the gas was perceived, the next 
three days were bright j but in the morning of the 
11th the sky was clouded ; a considerable increase of 
the volume of the gas was now observed: the 12th 
was cloudy, with gleams of sunshine ; there was still 
an increase, but less than in the bright days ; the 13th 
was bright. About nine o'clock A.M. on the 14th 
the receiver was quite full ; and considering the ori- 
ginal quantity in the jar, it must have been increased 
by at least 30 cubical inches of elastic fluid : at times 
during this day globules of gas escaped. At ten on 
the morning of the 15th, I examined a portion of the 
gass ; it contained less than JL of carbonic acid gas : 
J 00 parts of it exposed to the impregnated solution 
left only 75 parts ; so that the airjvas four per cent, 
purer than the air of theLtmosghere. * . 

I shall detail another similar experiment made 
v/ith equally decisive resiLihs.- : A- shoot from a vine, 
having three healthy leaves belorigiiig to it, attached 

c^r, : ,.^ — r^- — 

* See Fif. 17. 

D 9 



[ 202 j ♦ 

to its parent tree, was bent so as to be placed under 
the receiver which had been used in the last experi- 
ment ; the water confining the common air was kept in 
the same manner impregnated with carbonic acid gas : 
the experiment was carried on from August 6th till 
August 14th, 1807; during this time, though the 
weather had been generally clouded, and there had 
been some rain, the volume of elastic fluid continued to 
increase. Its quality was examined on the morning of 
the 15th; it contained -'^ of carbonic acid gas, and 
100 parts of it afforded 23.5 of oxygene gas. 

These facts confirm the popular opinion, that 
when the leaves of vegetables perform their healthy 
functions, they tend to purify the atmosphere in the 
common variations of weather, and changes from light 
to darkness. 

In germination, and at the time of the decay of 
the leaf, oxygene must be absorbed ; but when it is 
considered how large a part of the surface of the 
earth is clothed with perennial grasses, and that half 
of the globe is always exposed to the solar light, it ap- 
pears by far the most probable opinion, that more 
oxygene is produced than consumed during the pro- 
cess of vegetation ; and that it is this circumstance 
which is the principal cause of the uniformity of the 
constitution of the atmosphere. 

Animals produce no oxygene gas during the ex- 
ercise of any of their functions and they are constantly 
consuming it ; but the extent of the animal, compar- 
ed to that of the vegetable, kingdom is very small j 
and the quantity of carbonic acid gas produced 



[ 203 J 

,:iii respiration, and in various processes of com- 
bustion and fermentation, bears a proportion ex- 
tremely minute to the whole volume of the atmos- 
phere : if every plant during the progress of its life 
makes a very small addition of oxygene to the air, and 
occasions a very small consumption of carbonic acid, 
the effect may be conceived adequate to the wants of 
nature. 

It may occur as an objection to these views, that 
if the leaves, of plants purify the atmosphere, towards 
the end of autumn, and through the winter, and early 
spring, the air in our climates must become impure, 
the oxygene in it diminish, and the carbonic acid gas 
increase, which is not the case ; but there is a very 
satisfactory answer to this objection. The different 
parts of the atmosphere are constantly mixed together 
by winds, which when they are strong, move at the 
rate of from 60 to 100 miles in an hour. In our win- 
ter, the south-west gales convey air, which has been 
purified by the vast forests and savannas of South 
America, and which, passing over the ocean, arrives 
in an uncontaminated state. The storms and tempests 
which often occur at the beginning, and towards the 
middle of our winter, and which generally blow 
from the same quarter of the globe, have a salutary 
influence. By constant agitation and motion, the 
equilibrium of the constituent parts of the atmosphere 
is preserved ; it is fitted for the purposes of life ; and 
those events, which the superstitious formerh refer- 
red to the wrath of heaven, or the agency of evil 
spirits, and in which they saw only disorder and con*- 



C 204 ] 

iusion, are demonstrated by science, to be ministra- 
tions of divine intelligence, and connected with the or- 
der and harmony of our system. 

I have i*easoned, in a former part of this Lecture, 
■ against the close analogy which some persons have as- 
sumed between the absorption of oxygene and the for- 
mation of carbonic acid gas in germination, and in the 
respiration of the foetus. Similar arguments will ap- 
ply against the pursuit of this analogy between the 
functions of the leaves of the adult plant, and those of 
the lungs of the adult animal. Plants grow vigorous- 
ly only when supplied with light ; and most species 
die if deprived of it. It cannot be supposed that the 
production of oxygene from the leaf, which is known 
to be connected with its natural colour, is the exertion 
of a diseased function, or that it can acquire carbon in 
the day-time, when it is in most vigorous growth, 
when the sap is rising, when all its powers of obtain- 
ing nourishment are exerted ; merely for the purpose 
af giving it off again in the night, when its leaves are 
closed, when the motion of the sap is imperfect, and 
when it is in a state approaching to that of quiescence. 
Many plants that grow upon rocks, or soils, contain- 
ing no carbonic matter, can only be supposed to ac- 
quire their charcoal from the carbonic acid gas in the 
atmosphere ; and the leaf may be considered at the 
same time as an organ of absorption, and an organ 
in which the sap may undergo different chemical 
changes. 

"When pure water only is absorbed by the roots 
of plants, the fluid, in passing into the leaves, will 



[ 205 J 

probably Rave greater power to absorb carbonic acid 
from the atmosphere, when the water is saturated with 
Carbonic acid gas, some of this substance, even in the 
sunshine, may be given off by the leaves; but a part of 
it likewise will be always decomposed, which has been 
proved by the experiments of M. Sennebier. 

When the fluid taken up by the roots of plants 
contains much carbonaceous matter,, it is probable 
that plants may give off carbonic acid from their leaves, 
even in the sunshine. In short, the function of the 
leaf must vary according to the composition of the sap 
passing through it. When sugar is to be produced, 
as in early spring at the time of the development of 
buds and flowers, it is probable that less oxygene will 
be given off, than at the time of the ripening of the 
seed, when starch, or gums, or soils, are formed; and 
the process of ripening the seed usually takes place 
when the agency of the solar light is most intense. 
Whentheacid juices of fruits become saccharine in the 
natural process of vegetation, more oxygene, there 
is every reason to believe, must be given off, or new- 
ly combined, than at other times; for, as it was shewn 
in the third Lecture, all the vegetable acids contain 
more oxygene than sugar. It appears probable, that 
in some cases, in which oily and resinous bodies are 
-formed in vegetation, water may be decomp®sed: its 
oxygene set free, audits hydrogene absorbed. 

I have already mentioned, that some plants pro- 
duce oxygene in pure water; Dr. Ingenhousz found 
Ithis to be the case with species of the confervse; I 
have tried the leaves of many plants, particularly those 



I 206 3 

that produce volatile oils. When such leaves are ex- 
posed in water saturated with oxygene gas, oxygene 
is given off in the solar light; but the quantity is very 
small and always hmited; nor have I been able to as- 
certain with certainty, whether the vegetative powers * 
of the leaf were concerned in the operation, though it 
seems probable. I obtained a considerable quantity of ' 
oxygene in an experiment made fifteen years ago,^ 
in which vine leaves were exposed to pure water; but 
on repeating the trial often since, the quantities have 
always been very much smaller; I am ignorant whe-^ 
ther this difference is owing to the peculiar»state of the^ 
leaves, or to some confervas which might have adher- 
ed to the vessel, or to other sources of fallacy. 

The most important and most common products of 
vegetables, mucilage, starch, sugar, and woody fibre, 
are composed of water, or the elements of water in^ 
their due proportion, and charcoal; and these, or some 
of them, exist in all plants; and the decomposition of 
carbonic acid, and the combination of water in vege- 
table structures, are processes which must occur al- 
most universally. 

When glutenous and albuminous substances ex 
ist in plants, the azote they contain may be suspected^ 
to be derived from the atmosphere; but no experi-^ 
ments have been made which prove this; they migh/' 
easily be instituted upon mushrooms and fungusses. 

In cases in which buds are formed, or shoots 
thrown forth from roots, oxygene appears to be uni 
formly absorbed, as in the germination of seeds. I 
exposed a small potatoe moistened with common wa 



E 207 J 

ter to 24 cubical inches of atmospherical air, at a tem- 
perature of 59°. It began to throw forth a shoot on 
the third day; when it was a half an inch long I ex- 
amined the air; nearly a cubical inch of oxygene was 
absorbed, and about three-fourths of a cubical inch of 
carbonic acid formed. The juices in the shoot separ- 
ated from the potatoe, had a sweet taste; and the ab- 
sorption of oxygene, and the production of carbonic 
acid, were probably connected with the conversion of 
a portion of starch into sugar. When potatoes that 
have been frozen are thawed, they become sweet; pr^D- 
bably oxygene is absorbed in this process; if so, the 
! change may be prevented by thawing them out of the 
i contact of air, under water, for instance, that has 
been recently boiled. 

In the tillering of corn that is, the production of 
li new stalks round the original plume, there is every rea- 
, son to believe that oxygene must be absorbed; for the 
I stalk at which the tillering takes place, always con- 
tains sugar, and the shoots arise from a part derived of 
light. The drill husbandry favours this process; for 
loose earth is thrown by hoeing round the stalks; they 
! are preserved from light, and yet supplied with oxy- 
gene. I have counted from forty to one hundred and 
1. twenty stalks; produced from a grain of wheat, in a 
moderately good crop of drilled wheat. And we are 
informed by Sir Kenelm Digby in 1 660, that there was 
in the possession of the Fathers of the Christian Doc- 
jtrine at Paris, a plant of barley which they, at that time, 
kept by them as a curiosity, and which consisted of 249 
stalks springing from one root, or grain; and in which 
ihey counted above 18,000 grains, or seeds of barley. 



[ 208 ] 

The great increase which takes place in the trans- 
plantation of wheat, depends upon the circumstance, 
that each layer thrown out in tillering may be remov- 
ed, and treated as a distinct plant. In the Philosophi- 
cal Transactions, Vol. LVIII, p. 203, the following 
r.tatement may be found : Mr. C. Miller, of Cam- 
bridge, sowed some wheat on the 2d of June, 1766 ; 
and on the 8th of August, a plant was taken and* 
separated into 18 parts, and replanted; these plants' 
were again taken up, and divided in the months off 
September and October, and planted separately to' 
stand the winter, which division produced 67 plants. 
They were again taken up in March and April, and 
produced 500 plants : the number of ears thus form- 
ed from one grain of wheat was 21109, which gave ' 
three pecks and three quarters of corn that weighed 
47lbs. 7ozs. J and that were estimated at 576840 ! 
grains. 

It is evident from the statements just given, that the 
change which takes place in the juices of the leaf by the 
the action of the solar light, must tend to increase the 
proportion of inflammable matter to their other con- 
stituent parts. And the leaves of the plants that grow; 
in darkness, or in shady places, are uniformly pale j 
their juices are watery and saccharine, and they do^ 
not afford oils or resinous substances. I shall detail 
an experiment on this subject, 

I took an equal weight, 400 grains, of the leaves '■ 
of two plants of endive, one bright green, which had 
grown fully exposed to light, and the other almost 
white, v/hich had teen secluded from light by being 



L 209 ] 

covered with a box; after being both acted upon for 
some time by boiling water, in the state of pulp, the 
undissolved matter was dried, and exposed to the 
action of warm alcohol. The matter from the green 
leaves gave it a tinge of olive; that from the pale leaves 
did not alter its colour. Scarcely any solid matter 
was produced by evaporation of the alcohol that had 
been digested on the pale leaves; whereas by the eva- 
poration of that from the green leaves, a considerable 
residuum was obtained, five grains of which were se- 
parated from the vessel in which the evaporation was 
carried on; they burnt with flame, and appeared partly 
matter analogous to resin. 53 grains of woody fibre 
were obtained from the green leaves, and only 31 
from the pale leaves. 

It has been mentioned in the Third Lecture, that 
the sap probably, in common cases, descends from the 
leaves into the bark; the bark is usually so loose in its 
texture, that the atmosphere may possible act upon it 
in the cortical layers; but the changes taking place in 
the leaves, appear sufficient to explain the difference be- 
tween the products obtained from the bark and from 
the alburnum; the first of which contains more carbo- 
naceous matter than the last. 

When the similarity of the elements of different 
vegetable products is considered, according to the 
views given in the third Lecture, it is easy to conceive 
how the different organized parts may be formed from 
the same sap» according to the manner in which it is 
acted on by heat, light, and air. By the abstraction 

ofoxygene, the different inflammable products, fixed 

k2 



[ 210 J 

and volatile oils, resins, camphor, woody fibre, &> 
may be produced from saccharine or mucilaginous 
fluids; and by the abstraction of carbon and hydro- 
gene, starch, sugar, the different vegetable acids and 
substances soluble in water, may be formed from high- 
ly combustible and insoluble substances. Even the 
limpid volatile oils which convey the fragrance of the 
flower, consist of different proportions of the same 
essential elements, as the dense woody fibre; and both 
are formed by different changes in the same organSj 
from the same materials, and at the same time. 

M. Vauquelin has lately attempted to estimate 
the chemical changes taking place in vegetation, by 
analysing some of the organized parts of the horse- 
chesnut in their different stages of growth. He found 
in the buds collected, March 7. 1812, tanning princi- 
ple, and albuminous matter capable of being obtained 
separately, but when obtained, combining with each 
other. In the scales surrounding the buds, he found 
the tanning principle, a little saccharine matter, resin, 
and a fixed oil. In the leaves fully developed, he dis- 
covered the same principles as in the buds; and in ad- 
diti<)n, a peculiar green resinous matter. The petals 
of the flower yielded a yellowish resin, saccharine mat- 
ter, albuminous matter, and a little* wax: the stamina 
afforded sugar, resin, and tannin. 

The young chesnuts examined immediately after 
their formation, afforded a large quantity of a matter 
which appeared to be a combination of albuminous 
matter and tannin. All the parts of the plant afford- 
ed saline combinations of the acetic and phosphonc 
acids. 



Fic}. 17. 



P. 201 




C 211 -] 

M. Vauquclin could not obtain a sufficient quan- 
tity of the sap of the horse-chesnut for examination; a 
circumstance much to be regretted; and he has not 
stated the relative quantities of the different substances 
in the buds, leaves, flowers, and seeds. It is proba- 
ble, however, from his unfinished details, that the 
quantity of resinous matter is increased in the leaf, and 
that the white fibrous pulp of the chesnut is formed 
by the mutual action of albuminous and astringent, 
matter, which probably are supplied by different cells 
or vessels. I have already mentioned* that the cam- 
bium, from which the new parts of the trunk and the 
branches appear to be formed, probably owes its pow- 
er of consolidation to the mixture of two different 
kinds of sap; one of which flows upwards from the 
roots; and other of which probably descends from the 
leaves. I attempted, in May l^O^, at the time the 
cambium was forming in the oak, to ascertain the na- 
ture of the action of the sap of the alburnum upon the 
juices of the bark. By perforating the alburnum in a 
young oak, and applying an exhausting syringe to the 
aperture, I easily drew out a small quantity of sap. 
I could not, however, in the same way obtain sap from 
the bark. I was obliged to recur to the solution of 
its principles in water, by infusing a small quantity of 
fresh bark in warm water; the liquid obtained in this 
way was highly coloured and astringent; and produc- 
ed an immediate precipitate in the alburnous sap, the 

• Page Iflf 



C 212 J 

taste of which was sweetish, aud slightly astringent, 
and which was colourless. 

The increase of trees and plants must depend 
upon the quantity of sap which passes into the organs 
upon the quality of this sap; and on its modification 
by the principles of the atmosphere. Water, as it is 
the vehicle of the nourishment of the plant, is the sub- 
stance principally given off by the leaves. Dr. Hales 
found, that a sunSower, in one day of twelve hours, 
transpired by its leaves one pound fourteen ounces of 
water, all of which must have been imbibed by its 
roots. 

The powers which cause the ascent of the sap 
have been slightly touched upon in the second and 
third Lectures. The roots imbibe fluids from the soil 
by capillary attraction; but this power alone is insuffi- 
cient to account for the rapid elevation of the sap into 
the leaves. This is fully proved by the following fact 
detailed by Dr. Hales, Vol. I. of the Vegetable Statics, 
page 1 1 4. A vine branch of four or five years old was 
cut through, and a glass tube carefully attached to 
it; this tube was bent as a siphon, and filled with quick- 
silver; so that the force of the ascending sap could be 
measured by its effect in elevating the quicksilver. In 
a few days it was found, that the sap had been propel- 
led forwards with so much force as to raise the quick- 
silver to S8 inches, which is a force considerably su- 
perior to that of the usual pressure of the atmosphere. 
Capillary attraction can only be exerted by the sur- 
faces of small vessels, and can never raise a fluid into 
tubes above the vessels themselves. 



I 213 ] 

I referred in the beginning of the Third Lecture 
to Mr. Knight's opinion, that the contractions and 
expansions of the silver grain in the alburnum, are 
the most efficient cause of the ascent of the fluids con- 
tained in its pores and vessels. The views of this ex- 
cellent physiologist are rendered extremely probable 
by the facts he has brought forwards in support of 
them. Mr. Knight found that a very small increase 
of temperature was sufficient to cause the fibres of the 
silver grain to separate from each other, and that a 
very slight diminution of heat produced their contrac- 
tion. The sap rises most vigorously in spring and 
autumn, at the time the temperature is variable ; and 
if it be supposed, that in expanding and contracting, 
the elastic fibres of the silver grain exercise a pressure 
upon the cells and tubes containing the fluid absorbed 
by the capillary attraction of the roots, this fluid must 
constantly move upwards towards the points where a 
supply is needed. 

The experiments of Montgolfier, the celebrated 
inventor of the balloon, have shewn that water may 
be raised almost to an indefinite height by a very 
small force, provided its pressure be taken off by con- 
tinued divisions in the column of fluid. This princi- 
ple, there is great reason to suppose, must operate in 
assisting the ascent of the sap in the cells and vessels 
of plants which have no rectilineal communication, 
and which every where oppose obstacles to the per- 
pendicular pressure of the sap. 

The changes taking place in the leaves and buds, 
and the degree of their power of transpiration, must 



[ 21^ ] 

be intimately connected likewise with the motion of 
the sap upwards. This is shewn by several experi- 
ments of Dr. Hales. 

A branch from an appple tree was separated and 
.introduced into water, and connected with a mercurial 
gage. When the leaves were upon it, it raised the 
mercury by the force of the ascending juices to four 
inches ; but a similar branch, from which the leaves 
were removed, scarcely raised it a quarter of an inch. 

Those trees, likewise, whose leaves are soi't and 
of a spongy texture, and porous at their upper sur- 
faces, displayed by far the greatest powers with regard 
to the elevation of the sap. 

The same accurate philosopher whom I have just 
quoted, found that the pear, quince, cherry, walnut, 
peach, gooseberry, water elder and sycamore, which 
have all soft and unvarnished leaves, raised the mer- 
cury under favourable circumstances from three to 
six inches. Whereas the elm, oak, chesnut, hazel, 
sallow, and ash, which have firmer and more glossy 
leaves, raised the mercury only from one to two 
inches. And the evergreens and trees bearing var- 
nished leaves, scarcely at all affected it ; particularly 
the laurel and the laurustinus. 

It will be proper to mention the facts which 
shew, that in many cases fluids descend through the 
bark ; they are not of the same unequivocal nature 
as those which demonstrate the ascent of the' sap 
through the alburnum ; yet many of them are satis- 
factory. 



C 215 3 

M Baisse placed branches of different trees in 
an i itiion of madder, and kept them there for a long 
tim. He found in all cases, that the wood became 
red before the bark ; and that the bark began to re- 
ceive no tinge till the whole of the wood was colour- 
ed, and till the leaves were affected ; and that the co- 
louring matter first appeared above, in the bark im- 
mediately in contact with the leaves. 

Similar experiments were made by M. Bonnet, 
and with analogous results, though not so perfectly 
distinct as those of M. Baisse. 

Du Hamel found, that in different species of the 
pine and other trees, when strips of bark were re- 
moved, the upper part of the wound only emitted fluid, 
whilst the lower part remained dry. 

This may likewise be observed in the summer 
in fruit trees, when the bark is wounded, the alburn- 
um remaining untouched. 

I have mentioned in the Third Lecture, that when 
new bark is formed to supply the place of a ring 
that has been stripped off, it first makes its appearance 
upon the upper edge of the woun4, and spreads slow- 
ly downwards ; and no new matter appears from be- 
low rising upwards, if the experiment has been care- 
fully performed. I say carefully performed j because, if 
any of the interior cortical layer be suffered to remain 
communicating with the upper edge, new bark cover- 
ed with epidermis will form below this, and appear a:> 
if protruded upon the naked alburnum, and formed 
within the wound ^ and such a circiim^fancs would 
give ris6 to erroneous conclusions. 



C 216 3 

In the summer of 1 804, I examined some elms 
at Kensington. The bark of many of them had been 
very much injured, and in some cases more than a 
square foot had been stripped off. In most of the 
wounds the formation of the new cortical layers was 
from above, and gradually extending downwards 
^ round the aperture j but in two instances there had 
been very distinctly a formation of bark towards the 
lower edge. I was at first very much surprised at 
this appearance, so contradictory to the general 
opinion ; but on passing the point of a pen-knife along 
the surface of the alburnum, from below upwards, I 
found that a part of the cortical layer, which was of 
the colour of the alburnum, had remained communi- 
cating with the upper edge of the wound, and that 
the new bark had formed from this layer. I have had 
no opportunity of looking at the trees lately ; but I 
doubt not that the phasnomenon may still be observ- 
ed ; for some years must elapse before the new forma- 
tions will be complete. 

In accounting for the experiment of M. Palisot 
de Beauvois, mentioned in the Third Lecture, it may 
be supposed that the cortical fluid flowed down the 
alburnum upon the insulated bark, and thus occasion- 
ed its increase ; or it may be conceived that the barh 
itself contained sufficient cortical fluid at the time of 
its separation to form new parts by its action upon the 
alburnous fluid. 

The motion of the sap through the bark seems 
principally to depend upon gravitation. When the 
watery particles have been considerably dissipated 



C 217 ] 

by the transpiring functions of the leaves, and the mu. 
cilaginous, inflammable, and astringent constituents^ 
increased by the agency of heat, light, and air, the 
continued impulse upwards from the alburnum, forces 
the remaining inspissated fluid into the cortical vesselsj 
which receive no other supply. In these, from its 
weight, its natural tendency must be to descend; 
and the rapidity of the descent must depend upon 
the general consumption of the fluids of the bark 
in the living processes of vegetation; for there is every 
reason to believe, that no fluid passes into the soil 
through the roots; and it is impossible to conceive a 
free lateral communication between the absorbent ves- 
sels of the alburnum in the roots, and the transport- 
ing or carrying vessels of the bark; for if such a com- 
munication existed, there is no reason why the sap 
should not rise through the bark as well as through 
the alburnum; for the same physical powers would 
then operate upon both. 

Some authors have supposed that the sap rises in 
the alburnum, and descends through the bark in con- 
sequence of a power similar to that which produces the 
circulation of the blood in animals; a force analagous 
to the muscular force in the sides of the vessels. 

Dr. Thomson, in his System of Chemistry, has 
stated a fact which he considers as demonstrating the 
irritability of living vegetable systems. When a stalk 
of spurge (Euphorbia peplis) is separated by two in- 
cisions fr®m its leaves and roots, the milky fluid flows 
through both sections. Now, says the ingenious au- 
thor, it is impossible that this, could happen without 

F 2 



C 218 ] 

the living action of the vessels, for they cannot have 
been more than fullj and their diameter is so small, 
that if it were to continue unaltered, the capillary at- 
traction would be more than sufficient to contain their 
contents, and consequently not a drop would flow out. 
Since therefore the liquid escapes, it must be driven 
out by a force different from a common physical force. 

To this reasoning it may be answered, that tife 
sides of all the vessels are soft, and capable of collaps- 
ing by gravitation, as veins do in animal systems long 
after they have lost all their vitality; which is an effect 
totally different from vital or irritable action; and the 
phasnomenon may be compared to that of puncturing 
a vessel of elastic gum filled with fluid, both above and 
below; the fluid will make its way through the Zr 
pertures, though in much larger quantity from the 
lowest, which I have found is likewise the case with th;. 
.spurge. 

Dr. Barton has stated, that plants grow more vi^ 
gorously in water in which a little camphor has been 
infused. This has been brought forward as a fact in 
favour of the irritability of the vegetable tubular sys- 
tem. It is said that camphor can only be conceived 
to act as a stimulus, by increasing the living powers 
of the vessels, and causing them to contract with more 
energy. But this kind of speculation is very unsatis- 
factory. Camphor, we know, has a disagreeable pun- 
gent taste, and powerful smell; but physicians are far 
from being agreed whether it is a stimulant or sedative, 
even in its operation upon the human body. We 
should have no right whatever, even supposing the ir- 



C 219 3 

Stability of vegetables proved, to conclude, that be- 
cause camphor assisted the growth of plants, it acted 
on their living powers; and it is not right to infer the 
existence of a property proved in no other way, from 
the operation of uncertain qualities. 

That camphor may assist the growth of plants it 
is easy to conceive; and why should 5ve not consider 
its efficacy as similar to the efficacy of saccharine and 
mucilaginous matter, and particularly of oils, to which 
it is nearly allied in composition; and which afford 
food to the plant, and not stimulus; which are materi- 
als of assimilation, and not of excitement? 

The arguments in favour of a contraction similar 
to muscular action have not then much weight; and 
besides, there are direct facts which render the opinion 
highly improbable. 

When a single branch of a vine or other tree is 
introduced in winter into a hot-house, the trunk and 
the other bran<;hes remaining exposed to the cold at- 
mosphere, the sap will soon begin to move towards the 
buds in the heated branch; these buds will gradually 
unfold themselves and begin to transpire; and at length 
open into leaves. Now if any peculiar contractions of 
the sap vessels or cells were necessary for the ascent of 
the sap in the vessels, it is not possible that the applica- 
tion of heat to a single branch should occasion irrita- 
ble action to take place in a trunk many feet removed 
from it, or in roots fixed in the cold soil: but allowing 
that the energy of heat raises the fluid merely by di- 
minishing its gravity, increasing the facility of capillary 
action, and by producing an expansion of the fibre?. 



[220 ] 

of the silver grain, the phaenomenon is in perfect uni- 
6on with the views advanced in the preceeding part 
of this Lecture. 

The ilex, or evergreen oak, preserves its leaves 
through the winter, even when grafted upon the com- 
mon oak; and in consequence of the operation of the 
leaves there is a certain motion of the sap from the oak 
towards the ilex, which, as in the last case, seems to 
be inconsistent with the theory of irritable action. 

It is impossible to peruse any considerable part 
of the Vegetable Statics of Hales, without receiving a 
deep impression of the dependence of the motion of the 
sap upon common physical agencies. In the same tree 
this sagacious person observed, that in a cold cloudy 
morning when no sap ascended, a sudden change was 
produced by a gleam of sunshine, of half an hour; and a 
vigorous motion of the fluid. The alteration of the 
wind from south to the north immediately checked 
the effect. On the coming on of a cold afternoon after 
a hot day, the sap that had been rising began to, fall. 
A warm shower and a sleet storm produced opposite 
effects. 

Many of his observations likewise shew, that the 
different powers which act on the adult tree, produce 
different effects at different seasons. 

Thus in the early spring, before the buds ex- 
pand, the variations of the temperature, and changes 
of the state of the atmosphere with regard to moisture 
and dryness, exert their great effects upon the expan- 
sions and contractions of the vessels; and then the tree 
is in what is called by gardeners its bleeding season- • 



C 221 ] 

When the leaves are fully expanded, the great 
determination of the sap is to these new organs. And 
hence a tree which emits sap copiously from a wound 
whilst the buds are opening, will no longer emit it in 
summer when the leaves are perfect ; but in the varia- 
ble weather, towards the ends of autumn, when the 
leaves are falling, it will again possess the power of 

, bleeding in a very slight degree in the warmest days ; 

I but at no other times. 

I In all these circumstances there is nothing analo= 

gous to the irritable action of animal systems. 

In animal systems the heart and arteries are in 

I constant pulsation. Their functions are unceasingly 
performed in all climates, and in all seasons ; in win- 
ter, as well as in spring ; upon the arctic snows, and 
under the tropical suns. They neither cease in the 

I periodical nocturnal sleep, common to most animals ; 
nor in the long sleep of winter, peculiar to a few spe- 

I cies. The power is connected with animation, is lim- 
ited to beings possessing the means of voluntary lo- 
comotion ; it co-exists with the first appearance of 
vitality ; it disappears only with the last spark of life. 
Vegetables may be truly said to be living systems, 

|: in this sen^e, that they possess the means of convert- 

i ing the elements of common matter into organized 
structures, both by assimilation and reproduction j but 
we must not suffer ourselves to be deluded by the 
very extensive application of the word life, to conceive 

! hi the life of plants, any power similar to that produc- 
ing the life of animals. In calling forth the vegetable 

I functions, common physical agents alone seem to 



C 222 ] 

operate ; bilt in the animal system these agents are 
made subservient to a superior principle. To give the 
argument in plainer language, there are few philoso- 
phers who would be inclined to assert the existence 
of any thing above common matter, any thing imma- 
terial in the vegetable oeconomy. Such a doctrine is 
worthy only of a poetic form. The imagination may 
easily give Dryads to our trees, and Sylphs to our 
flowers ; but neither Dryads nor Sylphs can be ad- 
mitted in vegetable physiology ; and for reasons near- 
ly as strong, irritability and animation ought to be ex- 
eluded. 

As the operation of the different physical agents 
upon the sap vessels of plants ceases, and fluid be- 
comes quiescent, the materials dissolved in it by heat, 
are deposited upon the sides of the tubes now consi- 
derably diminished in their diameter ; and in conse- 
quence of this deposition, a nutritive matter is provi- 
ded for the first wants of the plant in early spring, to 
assist the opening of the buds, and their expansion^ 
when the motion from the want of leaves is as yet 
feeble. 

This beautiful principle in the vegetable oecono- 
my was first pointed out by Dr. Darwin ; and Mr. 
Knight has given a number of experimental elucida- 
tions of it. 

Mr. Knight made numerous incisions into the al- 
burnum of the sycamore and the birch, at different 
heights ; and in examining the sap that flowed from 
them, he found it more sweet and mucilaginous in 
proportion as the aperture from which it flowed was 



[ . 223 3 

elevated ; which he could ascribe to no other caus?^ 
than to its having dissolved sugar and mucilage, 
which had been stored up through the winter. 

He examined the alburnum in different poles of 
oak in the same forest : of which some had been fel- 
led in winter, and others in summer ; and he always 
found most soluble matter in the wood felled in win- 
ter, and its specific gravity was likewise greater. 

In all perennial trees this circumstance takes 
place ; and Ukewise in grasses and shrubs. The joints 
of the perennial grasses contain more saccharine and 
mucilaginous matter in winter than at any, other sea- 
son ; and this is the reason why the florin or Agros- 
tis alba, which abounds in these joints, affords so use- 
ful a winter food. 

The roots of shrubs contain the largest quantity 
of nourishing matter in the depth of winter j and the 
bulb in all plants possessing it, is the receptacle in 
which nourishment is hoarded up during winter. 

In annual plants the sap seem.s to be fully ex- 
hausted of all its nutritive matter by the production of 
flowers and seeds 5 and no system exists by which it 
can be preserved, 

When perennial grasses are cropped very close 
by feeding cattle late in autumn, it has been often ob- 
served by farmers, that they never rise vigorously 
in the spring ; and this is owing to the removal of 
that part ot the stalk which would have afforded them 
concrete sap, their first nourishment. 

Ship builders pref^ for their purposes that kind 
'^f oak timber afforded bv trees that have had their 



[ 5224 ] 

bark stripped off in spring, and which have been cut 
in the autumn or winter following. The reason of 
the superiority of this timber is, that the concrete 
sap is expended in the spring in the sprouting of the 
leaf ; and the circulation being destroyed, it is not 
formed anew ; and the wood having its pores fret 
from saccharine matter, is less liable to undergo fer- 
mentation from the action of moisture and air. 

In perennial trees a new alburnum, and conse- 
quently a new system of vessels, is annually produc- 
ed, and the nutriment for the next year deposited in 
them ; so that the new buds, like the plume of the 
seed, are supplied with a reservoir of matter essential 
to their first development. 

The old alburnum is gradually converted into 
heart-wood, and being constantly pressed upon by 
the expansive force of the new fibres, becomes harder, 
denser, and at length loses, altogether its vascular 
structure ; and in a certain time obeys the common 
laws of dead matter, decays, decomposes, and is con- 
verted into aeriform and carbonic elements ; into those 
principles from which it was originally formed. 

The decay of the heart- wood seems to constitute 
the great limit to the age and size of trees. And in 
young branches from old trees, it is much more liable 
:o decompose than in similar branches from seedlings, 
rhis is likewise the case with grafts. The graft is' 
only nourished by the sap of the tree to which it is 
transferred ; its properties are not changed by it ; the 
leaves, blossoms, and fruits are of the same kind as if 
it bad vegetated upon its parent stock. - The only ad- 



C 225 ] 

vantage to be gained in this way, is the affording to a 
graft from an old tree a more plentiful and heahhy 
food than it could have procured in its natural state ; 
it is rendered for a time more vigorous, and produces 
fairer blossoms and richer fruits. But it partakes not 
merely of the obvious properties, but likewise of the 
infirmities and dispositions to old age and decay, of 
the tree whence it sprung. 

This seems to be distinctly shewn by the obser- 
vations and experiments of Mr. Knight. He has, in a 
number of instances, transferred the young scions and 
healthy shoots from old esteemed fruit-hearing trees 
to young seedlings. They flourished for two or three 
years; but they soon became diseased and sickly like 
their parent trees. 

It is from this cause that so many of the apples 
formerly celebrated for their taste and their uses in the 
manufacture of cyder are gradually deteriorating, and 
many will soon disappear. The golden pippin, the 
red streak, and the moil, so excellent in the beginning 
of the last century, are now in the extremes! stage of 
their decay; and however carefully they are ingrafted, 
they merely tend to multiply a sickly and exhausted 
variety. 

The trees possessing the firmest and the least 
porous heart-wood are the longest in duration. 

In general the quantity of charcoal afforded by 
woods, offers a tolerable accurate indication of their 
durability: those most abundant in charcoal and earthy 
matter are most permanent; and those that contain the 



g2 



[ 226 ] 

largest proportion of gaseous elements are the most 
destructible. 

Amongst our own trees, the chesnut and the oak, 
are pre-eminent as to durabilityj and the chesnut af- 
fords rather more carbonaceous matter than the 
oak. 

In old Gothic buildings these woods have been 
sometimes mistaken one for the other; but they may 
be easily known by this circumstance, that the pore> 
in the alburnum of the oak are much larger and more 
thickly set, and are easily distinguished; whilst the 
pores in the chesnut require glasses to be seen dis- 
tinctly. 

In consequence of the slow decay of the heart- 
wood of the oak and the chesnut, these trees under 
favourable circumstances attain an age which cannot 
be much short of a 1000 years. 

The beech, the ash, and the sycamore, most like- 
ly never live half as long. The duration of the apple 
tree is not probably, much more than 200 years; but 
the pear tree, according to Mr. Knight, lives through 
double this period; most of our best apples are sup- 
posed to have been introduced into Britain by a fruit- 
erer of Henry the Eighth, and they are now in a state 
of old age. 

The oak and chesnut decay much sooner In a 
moist situation, than in a dry and sandy soil; and their 
timber is less firm. The sap vessels in such cases are 
more expanded, though less nourishing matter is car- 
ried into them; and the general texture of the forma- 
tions of wood necessarily less firm. vSuch" wood splits 



L 227 ] 

more easily, and is more liable to be affected by varia- 
tions in the state of the atmosphere. 

The same trees, in general, are much longer lived 
in the northern than in the southern climates. The 
reason seems to be, that all fermentation and decom- 
position are checked by cold; and at very low temper- 
atures both animal and vegetable matters altogether 
resist putrefaction: and in the northern winter, not 
only vegetable life, but likewise vegetable decay must 
be at a stand. 

The antiputrescent quality of cold chmates is ful- 
ly illustrated in the instances of the rhinoceros and 
mammoth lately found in Siberia, entire beneath the 
frozen soil, in which they must probably have existed 
from the time of the deluge. I examined a part of the 
skin of the mammoth, sent to this country, on which 
there was some coarse hairj it had all the chemical 
characters of recently dried skin. 

Trees that grow in situations much exposed to 
winds, have harder and firmer wood than such as are 
considerably sheltered. The dense sap is determined 
by the agitation of the smaller brances to the trunk 
and large branches; where the new alburnum formed 
is consequently thick and firm. Such trees abound in 
the crooked limbs fitted for forming knee-timber, 
which is necessary for joining the decks and sides of 
ships. The gales in elevated situations gradually act, 
so as to give the tree the form best calculated to resist 
their effects. And the mountain oak rises robust and 
sturdy; fixed firmly in the soil, and able to oppose the 
full force of the tempest. 



C 228 ] 

The decay of the best varieties of fruit-bearing 
trees which have been distributed through the country 
by grafts, is a circumstance of great importance. 
There is no mode of preserving them; and no re- 
source, except that of raising new varieties by seeds. 

"Where a species has been ameliorated by culture, 
the seeds it affords, other circumstances being similar, 
produce more vigorous and perfect plants; and in this 
way the great improvements in the productions of our 
fields and gardens seem to have been occasioned. 

Wheat in its indigenous state, as a natural pro- 
duction of the soil, appears to have been a very small 
grass: and the case is still more remarkable with the 
apple and the plum. The crab seems to have been the 
parent of all our apples. And two fruits can scarcely 
be conceived more different in colour, size, and ap^. 
pearance than the wild plum and the rich magnum 
bonum. 

The seeds of plants exalted by cultivation always 
furnish large and improved varieties; but the flavour, 
and even the colour of the fruit seems to be a matter 
of accident. Thus a hundred seeds of the golden 
pippin will all produce fine large-leaved apple trees, 
bearing fruit of a considerable size; but the tastes and 
colours of the apples from each will be different, and 
none will be the same in kind as those of the pippin 
itself. Some will be sweet, some sour, some bitter, 
some mawkish, some aromatic; some yellow, some 
green, some red, and some streaked. All the apples 
■will, however, be much more perfect thail those froni 
the seeds of a crab, which produce trees all of the same 
kind, and all bearing sour and diminutive fruit. 



[ 229 3 

I'he power of the horticulturist extends only to 
the multiplying excellent varieties by grafting. They 
cannot be rendered permanent; and the good fruits at 
present in our gardens, are the produce of a few seed- 
lings, selected probably from hundred of thousands ; 
the results of great labour and industry, and multipli- 
ed experiments. 

The larger and thicker the leaves of a seedling, 
and the more expanded its blossoms, the more it is 
hkely to produce a good variety of fruit. Short- 
leaved trees should never be selected ; for these ap- 
proach nearer to the original standard ; whereas the 
other qualities indicate the influence of cultivation. 

' In the general selection of seeds, it would appear 

that those arising from the most highly cultivated va- 
rieties of plants, are such as give the most vigorous 

I produce ; but it is necessary from time to time to 
change, and as it were, to cross the breed. 

I By applying the pollen, or dust of the stamina 

from one variety to the pistil of another of the same 
species, a new variety may be easily produced ; and 
Mr. Knight's experiments seem to warrant the idea, 

I that great advantages may be derived from this 
method of propagation. 

Mr. Knight's large peas produced by crossing 
two varieties, are celebrated amongst horticulturists, 
and will, I hope, soon be cultivated by farmers. 

I have seen several of his crossed apples, which 

' promise to rival the best of those which are gradually 

! %ing away in the cyder countries. 



[ 250 ] 

And his experiments on the crossing of wheat, 
which is very easily effected, merely by sowing the 
diflcrent kinds together, lead to a result which is of 
considerable importance. He says, in the Philosophi- 
cal Transactions for 1799, "in the years 1795 and 
1796, when almost the whole crop of corn in the 
island ^^ as blighted, the varieties obtained by crossing 
<7/o«^ escaped though sown in several soils, and in very 
different situations." 

The processes of gardening for increasing the 
number of fruit-bearing branches, and for improving 
the fruit upon particular branches, will all admit of 
elucidation from the principles that have been advan- 
ced in this Lecture. 

By making trees espaliers, the force of gravity is 
particularly directed towards the lateral parts of the 
branches, and more sap determined towards the fruit 
buds ; and hence they are more likely to bear when 
in a horizontal than when in a vertical position. 

The twisting of a wire, or tying a thread round 
a branch has been often recommended as a means of 
making it produce fruit. In this case the descent of 
the sap in the bark must be impeded above th^ liga- 
ture ; and more nutritive matter consequently retain- 
ed and applied to the expanding parts. 

In engrafting, the vessels of the bark of the stock 
and the graft cannot so perfectly come in contact as 
the alburnous vessels, which are as m6ch more nu- 
merous, and equally distributed ; hence the circulation 
downwards is probably impeded, and the tendency 
of the graft to evolve its fruit-bearing buds increased. 



L 231 ] 

By lopping trees, more nourishnient is supplied 
to the remaining parts ; for the sap flows laterally as 
well as perpendicularly. The same reasons will ap- 
ply to explain the increase of size of fruits by dimin- 
ishing the number upon a tree. 

As plants are capable ot amelioration by peculiar 
methods of cultivation, and of having the natural term 
of their duration extended ; so, in conformity to the 
general law of change, they are rendered unhealthy 
by being exposed to peculiar unfavourable circum- 
stances, and liable to premature old age and decay. 

The plants of warm climates transported into 
cold ones, or of cold ones transported into warm 
ones, if not absolutely destroyed by the change of situ- 
ation, are uniformly rendered unhealthy. 

Few of the tropical plants, as is well known, can 
be raised in this country, except in hot houses. The 
vine during the whole of our summer may be said to 
be in a feeble state with regard to health , and its 
fruit, except in very extraordinary cases, always con- 
tains a superabundance of acid. The gigantic pine of 
the north, when transported into the equatorial cli- 
mates, becomes a degenerated dwarf; and a great 
number of instances of the same kind misrht be 

o 

brought forward. 

Much has been written, and many very ingen- 
ious remarks have been made by different philoso- 
phers, upon what have been called the habits of plants. 
Thus; in transplanting a tree, it dies or becomes un- 
althy, unless its position wijh respect to the sun is 
I 'he same as before. The seeds brought from warm 



I 232 ] 

cliraatcb germinate here much more early in the sea- 
eon than the same species brought from cold chmates. 
The apple tree from Siberia,, where the short summer 
of three months immediately succeeds the long winter, 
in England, usually puts forths its blossoms in the 
first year of its transplantation, on the appearance of 
mild weather; and is often destroyed by the late 
frosts of the spring. 

It is not difficult to explain this principle so inti- 
mately connected with the healthy or diseased state of 
plants. The organization of the germ, whether in 
seeds or buds, must be different according as more or 
less heat or alternations of heat and cold have affected- 
it during its formation ; and the nature of its expah- 
sion must depend wholly on this organization. In a 
changeable chmate the formations will have been inter- 

o 

rupted, and in different successive layers. In an equa- 
ble temperature they will have been uniform ; and 
the operation of new and sudden causes will of course 
be sei^erely felt. 

The disposition of trees may, however, be chang- 
ed gradually in many instances ; and the operation of 
a new climate in this way be made supportable. The | 
myrtle, a native of the South of Europe inevitably 
dies if exposed in the early state of its growth to the 
frosts of our winter ; but if kept in a green-house 
during the cold seasons for successive years, and 
gradually exposed to low temperatures, it will, in an 
advanced stage of growth, resist even a very severe 
cold. And in the south and west of England the 
myrtle flourishes, produces blossoms and seeds, in 



C 233 ] 

consequence of this process, as an unprotected stan- 
dard tree ; and the layers from such trees are much 
more hardy than the layers from myrtles reared with- 
in doors. 

The arbutus, probably originally from similar 
cultivation, has become the principal ornament of the 
lakes of the south of Ireland. It thrives even in bleak 
mountain situations; and there can be little doubt but 
that the offspring of this tree inured to a temperate cli- 
mate might be easily spread in Biitain. 

The same principles that apply to the effects of 
heat and cold will likewise apply to the influence of 
moisture and dryness. The layers of a tree habitua- 
ted to a moist soil will die in a dry one: even though 
such a soil is more favourable to the general growth 
of the species. And, as was stated page 169, trees 
that have been raised in the centre of woods are soon- 
er or later destroyed, if exposed in their adult state to 
blasts, in consequence of the felling of the surround- 
ing timber. 

Trees, in all cases, in which they are exposed in 
high and open situations to the sun, the winds, and 
the rain, as I just now noticed, become low and ro- 
bust, exhibiting curved limbs, but never straight and 
graceful trunks. Shrubs and trees, on the contrary, 
which are too much sheltered, too much secluded 
from the sun and wind extend exceedingly in height^ 
but present at the same time slender and feeble 
branches, their leaves are pale and sickly, and in ex- 
treme cases they do not bear fruit The exclusion 
of light alone is sufficient to produce this species of 

H 2 



[ 234 3 ' 

disease, as would appear from the experiments g: 
Bonnet. This ingenious physiologist sowed three 
seeds of the pea in the same kind of soil: one he suf- 
fered to remain exposed to the free air; the other he 
inclosed in a tube of glass; and the third in a tube of 
wood. The pea in the tube of glass sprouted, and 
grew in a manner scarcely at all different from that 
under usual circumstances; but the plant in the tube 
of wood deprived of light, became white, and slender^ 
and grew to a much greater height. 

The plants growing in a soil incapable of supply- 
ing them with sufficient manure or dead organ- 
ized matter, are generally very low; having brown 
or dark green leaves, and their woody fibre abounds 
in earth. Those vegetating in peaty soils, or in lands 
too copiously supplied with animal or vegetable matter, 
rapidly expand, produce large bright green leaves, 
abound in sap, and generally blossom prematurely. 

Where a land is too rich for corn it is not an 
uncommon practice to cut down the first stalks, as by 
these means its exuberance is corrected, and it is less 
likely to fall before the grain is ripe; excess of poverty 
or of richness is almost equally fatal to the hopes of 
the farmer; and the true constitution of the soil for the 
best crop is that in which the earthy materials, the 
moisture and manure, are properly associated; and in 
which the decomposable vegetable or animal matter 
docs not exceed one-fourth of the weight of the earthy 
constituents. 

The canker, or erosion of the bark and wood, h 
A disease produced often in trees by a poverty of soilj 



[ 235 ] 

and it is invariably connected with old age. The cause 
seems to be an excess of alkaline and earthy matter 
in the descending sap. I have often found carbonate 
of lime on the edges of the canker in apple trees; and 
ulmin, which contains fixed alkali, is abundant in the 
canker of the elm. The old age of a tree, in this res- 
pect, is faintly analogous t-o the old age of animals, in 
which the secretions of solid bony matter are always in 
excess, and the tendency to ossification great. 

The common modes of attempting to cure the 
canker, are by cutting the edges of the bark, binding 
new bark upon it, or laying on a plaister of earth; but 
these methods, though they have been much extolled, 
probably do very little in producing a regeneration of 
the part. Perhaps the application of a weak acid to 
the canker might be of use; or where the tree is of 
great value, it may be watered occasionally with a very 
diluted acid. The alkaline and earthy nature of the 
morbid secretion warrants the trial; but circumstances 
that cannot be foreseen may occur to interfere with the 
success of the experiment. 

Besides the diseases having their source in the 
constitution of the plant, or in the unfavourable opera- 
tion of external elements, th^re are many others per- 
haps more injurious, depending upon the operations 
and powers of other living beings; and such are the 
most difficult to cure, and the most destructive to the 
labours of the husbandman. 

Parasitical plants of different species which at- 
tach themselves to trees and shrubs, feed on their 
juices, destroy their health, and finally their life. 



C 236 J 

abound in all climates; and are, perhaps, the most for- 
midable of the enemies of the superior and cultivated 
vegetable species. 

The mildew, which has often occasioned great 
havock in our wheat crops, and which was particular- 
ly destructive in 1804, is a species of fungus, so small 
as to require glasses to render its form distinct, and 
rapidly propagated by its seeds. 

This has been shewn by various botanists; and 
the subject has received a full illustration from the en- 
lightened and elaborate researches of the President of 
the Roval Society. 

The fungus rapidly spreads from stalk to stalk, 
fixes itself in the cells connected with the common 
tubes, and carries away and consumes that nourish- 
Cient# which should have been appropiated to the 
grain. 

No remedy has as yet been discovered for this 
disease; but as the fungus increases by the diffusion of 
its seeds, great care should be taken that no mildewed 
straw is carried in the manure used for corn; and in 
the early crop, if mildew is observed upon any of the 
stalks of corn, they should be carefully removed and 
treated as weeds. 

The popular notion amongst farmers, that a bar- 
berry-tree in the neighbourhood of a field of wheat of- 
ten produces the mildew, deserves examination. This 
tree is frequently covered with a fungus, which if it 
should be shewn to be capable of degenerating into the 
wheat fungus would offer an easy explanation of the 
effect. 



[ 237 3 

There is every reason to believe, from the re- 
searches of Sir Joseph Banks, that the smut in wheat 
is produced by a very small fungus which fixes on 
the grain : the products that it affords by analysis are 
similar to those afforded by the puff-ball ; and it is 
difficult to conceive, that without the agency of some 
organized structure, so complete a change should be 
effected in the constitution of the grain. 

The mistletoe and the ivy, the moss and the 
fichen, in fixing upon trees, uniformly injure their ve- 
getative processess, though in very different degrees. 
They are supported from the lateral sap vessels, and 
deprive the branches above of a part of their nourish- 
ment. 

The insect tribes are scarcely less injurious than 
^he parasitical plants. 

To enumerate all the animal destroyers and ty- 
rants of the vegetable kingdom would be to give a ca- 
talogue of the greater number of the classes in zoolo- 
gy. Every species of plant almost is the peculiar 
resting place, or dominion of some insect tribe ; and 
from the locust, the caterpillar, and snail, to the mi- 
nute aphis, a wonderful variety of the inferior insects 
are nourished, and live by their ravages upon the ve* 
getable world. 

I have already referred to the insect which feeds 
on the seed-leaf of the turnip. 

The Hessian fly, still more destructive to wheat, 
has in some seasons threatened the United States with 
a famine. And the French government is* at this 

* January 1813. 



[ 238 ] 

time issuing decrees with a view to accasion the des- 
truction of the larvae of the grasshopper. 

In general, wet weather is most favourable to the 
propagation of mildew, funguses, rust, and the small 
parasitical vegetables ; dry weather to the increase of 
the insect tribes. Nature, amidst all her changes, is 
continually directing her resources towards the pro- 
duction and multiplication of life ; and in the wise and 
grand economy of the whole system, even the agents 
that appear injurious to the hopes, and destructive to 
the comforts of man, are in fact ultimately connected 
with a more exalted state of his powers and his condi- 
tion. His industry is awakened, his activity kept 
alive, even by the defects of climates and season. By 
the acccidents which interfere with his efforts, he is 
made to exert his talents, to look farther into futurity, 
and to consider the vegetable kingdom not as a secure 
and inalterable inheritance, spontaneously providing 
for his wants ; but as a doubtful and insecure posses- 
sion, to be preserved only by labour, and extended 
and perfected by ingenuity. 



239 



LECTURE Vl. 

Of Manures of vegetable and animal Origin, Of the 
Manner in which they become the "Nourishment of the 
Plant. Of Fermentation and Putrefaction. Of the 
different Species of Manures of vegetable Origin ; of 
the different Species of anifiial Origin. Of mixed 
Manures. General Principles with Respect to the 
Use and .Application of such Manures, 

THAT certain vegetable and animal substances 
introduced into the soil accelerate vegetation and in- 
crease the produce of crops, is a fact known since the 
earliest period of agriculture ; but the manner in 
which manures act, the best modes of applying them, 
their relative value and durability, are still subjects of 
discussion. In this Lecture I shall endeavour to lay 
down some settled principles on these objects ; they 
are capable of being materially elucidated by the re- 
cent discoveries in chemistry ; and I need not dwell 
on their gr^at importance to farmers. 

The pores in the fibres of the roots of plants are 
so small, that it is with difficulty they can be discovered 
by the microscope ; it is not therefore probable, that 
solid substances can pass into them from the soil. I 
tried an experiment on this subject : some impalpa- 
ble powdered charcoal procured by washing gunpow- 



L 240 J 

der was placed in a phial (^ntaining pure water, in 
which a plant of peppermint was growing : the roots 
of the plant were pretty generally in contact with the 
charcoal. The experiment was made in the beginning 
of May, 1805 ; the gr®wth of the plant was very vi- 
gorous during a fortnight, when it was taken out of 
the phial ; the roots were cut through in different 
parts ; but no carbonaceous matter could be disco- 
vered in them, nor were the smallest fibrils blackened 
by charcoal, though this must have been the case had 
the charcoal been absorbed in a solid form. 

No substance is more necessary to plants than 
carbonaceous matter ; and if this cannot be introdu- 
ced into the organs of plants except in a state of solu- 
tion, there is every reason to suppose that other sub- 
stances less essential will be in the same case. 

I found by some experiments made in 1804, that 
plants introduced into strong fresh solutions of sugar, 
mucilage, tanning principle, jelly, and other substan- 
ces died ; but that plants Hved in the same solutions 
after they had fermented. At that time, I supposed 
that fermentation was necessary to prepare the food 
of plants ; but I have since found that the deleterious 
effect of the recent vegetable solutions was owing to 
their being too concentrated ; in consequence of which 
the vegetable organs were probably clogged with so- 
lid matter, and the transpiration by the leaves pre- 
vented. In the beginning of June, in the next year, 
I used solutions of the same substances, but so much 
diluted, that there was only about 200 P^i^t of solid ve- 
getable or animal matter in the solutions. Plants of 



C 241 ] 

nvnt grew luxuriantly in all these solutions ; but least 
so in that of the astringent matter. I watered some 
spots, of grass in a garden with the different solutions 
separately, and a spot with common water : the grass 
watered with- solutions of jelly, sugar, and mucilage 
grew most vigorously ; and that watered with the so- 
lution of the tanning principle grew better than that 
watered with common water. 

I endeavoured to ascertain whether soluble vegetable 
substances passed in an unchanged state into the roots 
of plants, by comparing the products of the analysis 
of the roots of some plants of mint which had grown, 
some in common water, some in a solution of sugar. 
1 20 grains of the roots of the mint which grew in the 
solution of sugar, afforded five grains of pale green 
extract, which had a sweetish taste, but which slightly 
coagulated by the action of alcohol. 120 grains of 
the roots of the mint which had grown in common 
water yielded three grains and a half of extract, which 
was of a deep olive colour ; its taste was sweetish, 
but more astringent than that of the other extract, 
and it coagulated more copiously with alcohol. 

These results, though not quite decisive, favour 
the opinion that soluble matters pass unaltered into 
the roots of plants ; and the idea is confirmed by the 
circumstance that the radical fibres of plants made to 
grow in infusions of madder are tinged red ; and it may 
be considered as almost proved by the fact, that sub- 
stances which are even poisonous to vegetables are ab- 
sorbed by them. I introduced the roots of a primrose 
into a weak solution of oxide of iron in vinegar, and 

i2 



[ 242 ] 

suffered it to remain in it till the leaves became yel- 
low ; the roots were then carefully washed in distil- 
led water, bruised, and boiled in a small quantity of 
the same fluid : the decoction of them passed through 
a filtre was examined by the test of infusion of nu't- 
galls ; the decoction gained a strong tint of purple, 
which proves that solution of iron had been taken up 
by the vessels or pores in the roots. 

Vegetable and animal substances, as is shewn by 
universal experience, are consumed in vegetation ; 
and they can only nourish the plant by affording soli4 
matters capable of being dissolved by water, or gas- 
eous substances capable of being absorbed by the 
fluids in the leaves of vegetables ; but such parts of 
them as are rendered gaseous, and that pass into the 
atmosphere, must produce a comparatively small ef- 
fect, for gasses soon become diffused through the 
mass of the surrounding air. The great object in the 
application of manure should be to make it afford as 
much soluble matter as possible to the roots of the 
plants ; and that in a slow and gradual manner, so 
that it may be entirely consumed in forming the sap 
or organized parts of the plant. 

Mucilaginous, gelatinous, saccharine, oily, and 
Extractive fluids, and solution of carbonic acid in wa- 
ter, are substances that in their unchanged states con- 
tain almost all the principles necessary for the life of 
plants ; but there are few cases in which they can be 
applied as manures in their pure forms ; and vegeta- 
ble manures, in general, contain a great excess of fib- 
rous and insoluble matter, which must undergo che- 



C 243 3 

mical changes before they can become the food of 
plants. 

It will be proper to take a scientific view of the 
nature of these changes ; of the causes which occasion ^ 
them, and which accelerate or retard them 5 and of 
the products they afford. 

If any fresh vegetable matter which contains su- 
gar, mucilage, starch, or other of the vegetable com- 
pounds soluble in water be moistened and exposed to 
air, at a temperature from 55° to 80°, oxygene will ^ 
soon be absorbed, and carbonic acid formed -, heat 
will be produced, and elastic fluids, principally car- 
bonic acid, gaseous oxide of carbon, and hydro- car- 
bonate will be evolved ; a dark coloured liquid of a 
slightly sour or bitter taste will likewise be formed ; 
and if the process be suffered to continue for a time 
sufficiently long, nothing solid will remain, except 
earthy and saline matter, coloured black by charcoal. 

The dark coloured fluid formed in the fermenta- 
tion always contains acetic acid ; and when albumen 
or gluten exists in the vegetable substance, it likewise 
contains volatile alkali. 

In proportion as there is more ]gluten, albumen, 
or matters soluble in water in the vegetable substances 
exposed to fermentation, so in proportion, all other 
circumstances being equal, will the process be more 
rapid. Pure woody fibre alone undergoes a change 
very slowly ; but its texture is broken down, and it is 
easily resolved into new elements when mixed with 
substances more liable to change, containing more 
oxygene and hydrogene. Volatile and fixed oils, resins 



C 244 ] 

and wax, are more susceptible of change than woody 
fibre when exposed to air and water ; but much 
less liable than the other vegetable compounds ; and 
even the most inflammable substances by the absorp- 
( I tion of oxygene, become gradually soluble in water. 

Animal matters in general are more liable to de- 
compose than vegetable substances ; oxygene is ab- 
sorbed, and carbonic acid and ammonia formed in the 
process of their putrefaction. They produce foetid 
j compound elastic fluids, and likewise azote : they af- 
ford dark coloured acid and oily fluids, and leave a 
residuum of salts and earths mixed with carbonace- 
ous matter. 

The principal substances which constitute the 
difl'erent parts of animals, or which are found in their 
blood, their secretions, or their excrements, are gela- 
tine, fibrine, mucus, fatty, or oily matter, albumen, 
urea, uric acid, and different acid, saline, and earthy 
matter. 

Of these gelatine is the substance which when 
combined with water forms jelly. It is very liable to 
putrefaction. According to M. M. Gay Lussac and 
Thenard, it is composed of 
47.88 of carbon, 
27.207 — oxygene, 
7.9 1 4 — hydrogene. 
16.998 

These proportions cannot be considered as defi- 
nite, for they do not bear to each other the ratios 
of any simple multiples of the number represent- 
ing the elements j the case seems to be the same 



C 245 ] 

j with other animal compounds : and even in ve- 
jgetable substances, in general, as appears from the 
! statements given in the Third Lecture, the propor- 
! tions are far from having the same simple relations 
i as in the binary compounds capable of being made* 
.artificially, such as acids, alkalies, oxides, and in 
j salts. 

I Fibrine constitutes the basis of the muscular 

fibre of animals, and a similar substance may be ob- 
jtained from recent fluid blood ; by stirring it with a 
ji stick the fibrine will adhere to the stick. It is not 
(soluble in water j but by the action of acids, as Mr. 
[Hatchett has shewn, it becomes soluble, and analo- 
gous to gelatine. It is less disposed to putrefy than 
.gelatine. According to M. M. Gay Lussac and Then- 
ard, 100 parts of fibrine contain 

Of carbon - - 53.360 

— oxy^ene - - 19.685 

— hydrogene - - 7.021 

— azote - - 19.934 

Mucus is very analogous to vegetable gum in its 
jcharactersj and as Dr. Bostock has stated, it may be 
jobtained by evaporating saliva. No experiments have 
[Ibeen made upon its analysis; but it is probably similar 
jjto gum in composition. It is capable of undergoing 
'putrefaction, but less rapidly than fibrine. 

Animal fat and oils have not been accurately analy- 
Ijsed ; but there is great reason to suppose that their 
icomposition is analogous to that of similar substances 
Ifrom the vegetable kingdom. 

Albumen has been already referred to, and its 
..analysis stated in the Third Lectare. 



[ 246 ] 

Urea may be obtained by the evaporation of Inl- ^ 
man urine, till it is of the consistence of a syrup; and 
the action of alcohol on the crystalline substance which 
forms when the evaporated matter cools. In this 
way a solution of urea in alcohol is procured, and the i 
alcohol may be separated from the urea by heat, i 
Urea is very soluble in water, and is precipitated 
from water by diluted nitric acid in the form of 
bright pearl-coloured crystals; this property distin- 
guishes it from all other animal substances. 

According to Fourcroy and Vauquelin, lOOparts^ 
of urea when distilled yield. 

92.027 parts of carbonate of ammonia. 
4.608 carburetted hydrogene gas. 
3.225 of charcoal. 
Urea, particularly when mixed with albumen or, 
gelatine, readily undergoes putrefaction. 

Uric acid, as has been shewn by Dr. Egan, 
may be obtained from human urine by pouring an 
acid into it; and it often falls down from urine in' 
the form of brick-coloured crystals. It consists of 
carbon, hydrogene, oxygene and azote; but their] 
proportions have not yet been determined. Uric 
acid is one of the animal substances least liable to 
undergo the process of putrefaction. 

According to the different proportions of these 
principles in animal compounds, so are the changes 
they undergo different. When there is much saline 
or earthy matter mixed or combined with them, the 
progress of their decomposition is less rapid than when 
they are principally composed of fibrine, albumen, 
gelatine, or urea. 



[ 247 ] 

The ammonia given off from animal compounds 

in putrefaction may be conceived to be formed at the 

time of their decomposition by the combination of hy- 

I drogene and azote ; except this matter, the other pro- 

1 ducts of putrefaction are analogous to those afforded 

; by the fermentation of vegetable substances ; and the 

I soluble substances formed abound in the elements, 

which are the constituent parts of vegetables, in car- 

' bon, hydrogene, and oxygene. 

Whenever manures consist principally of matter 
; soluble in water, it is evident that their fermentation 
{ or putrefaction should be prevented as much as pos- 
sible ; and the only cases in which these processes can 
; be useful, are when the manure consists principally ' 
: of vegetable or animal fibre. The cii'cumstances ne- 
' cessary for the putrefaction of ani;nal substances are 
j similar to those required for the fermentation of vege- 
table substances ; a temperature above the freezing 
point, the presence of water, and the presence of oxy- 
gene, at least in the first stage of the process. 

To prevent manures from decomposing, they 
should be preserved dry, defended from the contact 
i' of air, and kept as cool as possible. 

Salt and alcohol appear to owe their powers of 
preserving animal and vegetable substances to their at- 
traction for water, by which they prevent its decom- 
posing action, and likewise to their excluding air. The 
j use of ice in preserving animal substances is owing to 
its keeping their temperature low. The efficacy of 
M. Appert's method of preserving animal and vegeta- 
ble substances, an account of which has been lately 



1 24* ] 

published, entirely depends upon the exclusion of air. \ 
This method Is by filHng a vessel of tin plate or glass 
. with the meat or vegetables ; soldering or cementing I 
\j the top so as to render the vessel air tight ; and then 
keeping it half immersed in a vessel of boiling water t 
for a sufficient time to render the meat or vegetables 
proper for food. In this last process it is probable 
that the small quantity of oxygene remaining in the 
vessel is absorbed : for on opening a tinned iron can- 
ister which had been filled with raw beef and exposed 
to hot water the day before, I found that the minute 
quantity of elastic fluid which could be procured from 
it, was a mixture of carbonic acid gas and azote. 

Where meat or vegetable food is to be preserved 
on a large scale, for the use of the navy or army for 
instance, I am inclined to believe, that by forcibly 
throwing a quantity of carbonic acid, hydrogene, or 
azote into the vessel, by means of a compressing 
pump, similar to that used for making artificial Seltzer 
water, any change in the substance would be more 
effectually prevented. No elastic fluid in this case 
would have room to form by the decomposition of 
the meat ; and the tightness and strength of the ves- 
sel would be proved by the process. No putrefaction 
• or fermentation can go on without the generation of 
elastic fluid ; and pressure would probably act with 
as much efficacy as cold in the preservation of animal 
or vegetable food. 

As different manures contain difl^erent propor- 
tions of the elements necessary to vegetation, so they 
require a different treatment to enable them to pro- 



L 249 ] 

duce their full effects in agriculture. I shall therefore 
describe in detail the properties and nature of the 
manures in common use, and give some general views 
respecting the best modes of preserving and applying 
jhem. 

Ail green succulent plants contain saccharine or 
mucilaginous matter, with woody fibre, and readily 
ferment. They cannot, therefore, if intended for ma- 
nure, be used too soon after their death. 

When gree7i crops are to be employed for enrich- 
ing a soil, they should be ploughed in, if it be possi- 
ble, when in flower, or at the time the flower is begin- 
ing to appear, for it is at this period that they contain 
the largest quantity of easily soluble matter, and that 
their leaves are most active in forming nutritive mat- 
ter. Green crops, pond weeds, the paring of hedges 
or ditches, or any kind of fresh vegetable matter, re- 
quires no preparation to fit them for manure. The 
decomposition slowly proceeds beneath the soil; the 
soluble matters are gradually dissolved, and the slight 
fermentation that goes on checked by the want of a 
free communication of air, tends to render the woody 
fibre soluble without occasioning the rapid dissipation 
of elastic matter. 

When old pastures are broken up and made 
arable, not only has the soil been enriched by the 
death and slow decay of the plants which have left 
soluble matters in the soil ; but the leaves and roots 
of the grasses living at the time and occupying so 
large a part of the surface, afford saccharine, mucila- 
ginous, and extractive matters, which become imme* 

k2 



[ 250 3 

diately the food of the crop, and the gradual decom- 
position affords a supply for successive years. 

Rape cake, which is used with great success as a 
manure, contains a large quantity of mucilage, some 
albuminous matter, and a small quantity of oil. This 
manure should be used recent, and kept as dry as pos- 
sible before it is applied. It forms an excellent dres- 
sing for turnip crops ; and is most oeconomically ap- 
plied by being thrown into the soil at the same time 
with the seed. Whoever wishes to see this practice 
in its highest degree of perfection, should attend Mr. 
Coke's annual sheep-shearing at Holkham. 

Malt dust consists chiefly of the infant radicle 
separated from the grain. I have never made any ex- 
periment upon this manure ; but there is great reason 
to suppose it must contain saccharine matter ; and this 
will account for its powerful effects. Like rape cake 
it should be used as dry as possible, and its fermenta- 
tion prevented. 

Linseed cake is too valuable as a food for cattle 
to be much employed as a manure ; the analysis of 
linseed was referred to in the Third Lecture. The 
;water in vAi\z\iflax and hemp are steeped for the pur- 
pose of obtaining the pure vegetable fibre, has consi- 
derable fertilizing powers. It appears to contain a 
substance analogous to albumen, and likewise much 
vegetable extractive matter. It putrefies very readily. 
A certain degree of fermentation is absolutely neces- 
sary to obtain the flax and hemp in a proper state ; 
the water to which they have been exposed should 



C 251 ] 

therefore be used as a manure as soon as the vegeta- 
ble fibre is removed from it. 

Sea weeds^ consisting of different species offuci, 
algae, and confervce, are much used as a manure on 
the sea coasts of Britain and Ireland. By digesting 
the common fucus, which is the sea weed usually most 
abundant on the coast, in boiling water, I obtained 
from it one-eighth of a gelatinous substance which 
had characters similar to mucilage. A quantity dis- 
tilled gave nearly four-fifths of its weight of water, 
but no ammonia ; the water had an empyreumatic and 
slightly sour taste ; the ashes contained sea salt, car- 
bonate of soda, and carbonaceous matter. The gase- 
ous matter afforded was small in quantity, principally 
carbonic acid and gaseous oxide of carbon, with a lit- 
tle hydro-carbonate. This manure is transient in its 
effects, and does not last for more than a single crop, 
which is easily accounted for from the large quantity 
of water, or the elements of water, it contains. It de- 
cays without producing heat when exposed to the at- 
mosphere, and seems as it were to melt down and dis- 
solve away. I have seen a large heap entirely des- 
troyed in less than two years, nothing remaining but 
a little black fibrous matter. 

I suffered some of the firmest part of a fucus to 
remain in a close jar containing atmospheric air for a 
fortnight : in this time it had become very much 
shrivelled j the sides of the jar were lined with dew. 
The air examined was found to have lost oxygene, 
and contained carbonic acid gas. 

Sea weed is sometimes suffered to ferment be- 
fore it is used ; but this process seems wholly unne- 



[ 252 ] 

cessary, for there is no fibrous matter rendered solu- 
ble in the process, and a part of the manure is lost. 

The best farmers in the west of England use it 
as fresh as it can be procured ; and the practical- 
results of this mode of applying it are exactly confor- 
mable to the theory of its operation. The carbonic 
acid formed by its incipient fermentation must be part- 
ly dissolved by the water set free in the same pro- 
cess J aqd thus become capable of absorption by the 
roots of plants. 

The effects of the sea weed as manure must prin- 
cipally depend upon this carbonic acid, and upon the 
soluble mucilage the weed contains ; and I found that 
some fucus which had fermented so as to have lost 
about half its weight, afforded less than A of mucila- 
ginous matter ; from which it may be fairly conclud- 
ed that some of this substance is destroyed in fermen- 
tation. 

Dry j/r^z'a' of wheat, oats, barley, beans and peas, 
and spoiled hay, or any other similar kind of dry ve- 
getable matter is, in all cases, useful manure. In 
general, such substances are made to ferment before 
they are employed, though it may be doubted whether 
the practice should be indiscriminately adopted. 

From 400 grains of dry barley straw I obtained 
eight grains of matter soluble in water, which had a 
brown colour, and tasted like mucilage. From 400 
grains of wheaten straw I obtained five grains of a 
similar substance. 

There can be no doubt that the straw of differ- 
ent crops immediately ploughed into the ground af- 



[ 253 ] 

fords nourishment to plants ; but there is an objec- 
tion to this method of using straw from the difficulty 
of burying long straw, and from it^ rendering the 
husbandry foul. 

When straw is made to ferment it becomes a 
more manageable manure ; but there is likewise on 
the whole a great loss of nutritive matter. More 
manure is perhaps supplied for a single crop ; but the 
land is less improved than it would be, supposing the 
whole of the vegetable matter could be finely divide^ 
and mixed with the soil. 

It is usual to carry straw that can be employed 
for no other purpose to the dunghill, to ferment, and 
decompose ; but it is worth experiment, whether it 
may not be more ceconomically applied when chopped 
small by a proper machine, and kept dry till it is 
ploughed in for the use of a crop. In this case, 
though it would decompose much more slowly and 
produce less effect at first, yet its influence would be 
much more lasting. 

Mere woody fibre seems to be the only vegetable 
matter that requires fermentation to render it nutritive 
to plants. Tanners sptnt hark is a substance of this 
kind. Mr. Young, in his excellent Essay on Ma- 
nures, which gained him the Bedfoi'dian medal of the 
Bath Agricultural Society, states, " that spent bark 
seemed rather to injure than assist vegetation;'* 
which he attributes to the astringent matter that it con- 
tains. But in fact it is freed from all soluble sub- 
'stances, by the operation of water in the tan-pit ; and 
if injurious to vegetation, the effect is probably owing 



L 254, 3 

to its agency upon water, or to its mechanical efFects. 
It is a substance very absorbent and retentive of mois- 
ture, and yet not penetrable by the roots of plants. 

Inert peaty matter is a substance of the same kind. 
It remains for years exposed to water and air without 
undergoing change ; and in this state yields little or 
no nourishment to plants. 

, Woody fibre will not ferment unless some sub- 
stances are mixed with it which act the same part as 
the mucilage, sugar, and extractive or albuminous 
matters, with which it is usually associated in herbs 
and succulent vegetables. Lord Meadowbank has 
judiciously recommended a mixture of common farm- 
yard dung for the purpose of bringing peats into fer- 
mentation ; any putrescible or fermentable substance 
will answer the end ; and the more a substance heats, " 
and the more readily it ferments, the better will it be ' 
fitted for the purpose. 

Lord Meadowbank states, that one part of dung " 
is sufficient to bring three or four parts of peat into a i 
state in which it is fitted to be applied to land ; but of I 
course the quantity must vary according to the nature ] 
of the dung and of the peat. In cases in which some j 
living vegetables are mixed with the peat, the fermen- 
tation will be more readily effected. , 

Tanners spent bark, shavings of wood and saw 
dust, will probably require as much dung to bring 
them into fermentation as the worst kind of peat. 

Woody fibre may be likewise prepared so as to 
become a manure by the action of lime. This subject 
I shall discuss in the next Lecture, as it follows na* 



[ 255 ] 

turally another series of facts, relating to the effects 
of lime in the soil. 

It is evident from the analysis of woody fibre by 
M. M. Gay Lussac and Thenard, (which shews that it 
consists principally of the elements of water and car- 
bon, the carbon being in larger quantities than in the 
other vegetable compounds) that any process which 
tends to abstract carbonaceous matter from it, must 
bring it nearer in composition to the soluble princi- 
ples ; and this is done in fermentation by the absorp- 
tion of oxygene and production of carbonic acid ; and 
a similar effect, it will be shewn, is produced by lime. 

Wood-ashes imperfectly formed, that is wood-ashes 
containing much charcoal, are said to have been used 
with success as a manure. A part of their effects 
may be owing to the slow and gradual consumption 
of the charcoal, which seems capable, under other 
circumstances than those of actual combustion, of ab- 
sorbing oxygene so as to become carbonic acid. 

An April, 1803, I inclosed some well burnt 
charcoal in a tube half filled with pure water, and half 
with common air ; the tube was hermetically sealed. 
I opened the tube under pure water in the spring of 
1 804, at a time when the atmospheric temperature and 
pressure were nearly the same as at the commence- 
ment of the experiment. Some water rushed in ; and 
on expelling a little air by heat from the tube, and 
analysing it, it was found to contain only seven per 
cent, of oxgene. The water in the tube, when mixed 
with limewater, produced a copious precipitate j so 



C 25G 3 

that carbonic acid had evidently been formed and 
dissolved by the water. 

Manures from animal substances, in general, re- 
quire no chemical preparation to fit them for the soil. 
The great object of the farmer is to blend them with 
earthy constituents in a proper state of division, and 
to prevent their too rapid decomposition. 

The entire parts of the muscles of land animals 
are not commonly used as manure, though there are 
many cases in which such an application might be 
easily made. Horses, dogs, sheep, deer, and other quad- 
rupeds that have died accidentally, or of disease, after 
their skins are separated, are often suffered to remain 
exposed to the air, or immersed in water till they are 
destroyed by birds or beasts of prey, or entirely de- 
composed ; and in this case most of their organized 
matter is lost for the land in which they lie, and a 
considerable portion of it employed in giving off nox- 
ious gasses to the atmosphere. 

By covering dead animals with five or six times 
their bulk of soil, mixed with one part of lime, and 
suffering them to remain for a few months ; their de- 
composition would impregnate the soil with soluble 
matters, so as to render it an excellent manure ; and 
by mixing a little fresh quicklime with it at the time of 
its removal, the disagreeable effluvia would be in a. 
great measure destr©yed ; and it might be applied in 
the same way as any other manure to crops. 

¥ish forms a powerful manure in whatever state 
it is applied ; but it cannot be ploughed in too fresh, 
though the quantity should be limited. Mr. Young 



L 257 ] 

records an experiment, in which herrings spread over 
a field and ploughed in for wheat, produced so rank V ' 
a crop, that it was entirely laid before harvest. 

The refuse pilchards in Cornwall are used 
throughout the county as a manure, with excellent 
effects. They are usually mixed with sand or soilj 
and sometimes with sea-weed, to prevent them from 
raising too luxuriant a crop. The effects are perceiv- 
ed for several years. 

In the fens of Lincolnshire, Cambridgeshire, and 
Norfolk, the little fish called sticklebacks, are caught 
in the shallow waters in such quantities, that they 
form a great article of manure in the land bordering 
on the fens. 

It is easy to explain the operation of fish as a 
manure. The skin is principally gelatine : which 
from its slight state of cohesion is readily soluble in 
water : fat or oil is always found in fishes, either un- 
der the skin or in some of the viscera ; and their fib- 
rous matter contains all the essential elements of vege- 
table substances. 

Amongst oily substances, graves and blubber are 
employed as manure. They are both most useful when 
mixed with soil, so as to expose a large surface to the 
air, the oxygene of which produces soluble matter 
from them. Lord Somerville used blubber with great 
success at his farm in Surrey. It was made into a 
heap with soil, and retained its powers of fertilizing 
for several successive years. 

The carbon and hydrogene abounding in oily 
substances fully account for their effects ; and their 

L 2 



[ 258 ] 

durability is easily explained from the gradual manner 
in which they change by the action of air and water. 

Bones are much used as a manure in the neigh- 
bourhood of London. After being broken and boiled 
for grease, they are sold to the farmer. The more 
divided they are, the more powerful are their effects. 
I'he expense of grinding them in a mill would proba- 
bly be repaid by the increase of their fertilizing pow- 
ers ; and in the state of powder they might be used in 
the drill husbandry, and delivered with the seed in the 
same manner as rape cake. 

Bone dust, and bone shavings, the refuse of the 
turning manufacture, may be advantageously employ- 
ed in the same way. 

The basis of bone is constituted by earthy salts, 
principally phosphate of lime, with some carbonate of 
lime and phosphate of magnesia ; the easily decom- 
posable substances in bone are fat, gelatine, and cartil- 
age, which seems of the same nature as coagulated 
albumen. 

According to the analysis of Fourcroy and Vau- 
quelin, ox bones are composed 

Of decomposable animal matter 5 1 

— phosphate of lime - - 37.7 

— carbonate of lime - - 10 

— phosphate of magnesia - 1.3 

100 

M. Merat Guillot has given the following esti- 
mate of the composition of the bones of different 
animals. 



259 



i 


Phosphate 
of lime. 


Carbonate 
of lime. 


Bone of Calf 
Horse 

1 Elk 

Hog 

Hare 

Pullet 

Pike 

Horses' leeth 

Ivory 

Hartshorn 


54 

67.5 
70 
OO 
52 
85 
72 
64 
45 

85.5 
64 
27 


1.25 

s 
1 
I 
1 

1.5 
1 

5 

25 
1 

1 



The remaining parts of the 100 must be consi- 
dered as decomposable animal matter. 

Horn is a still more powerful manure than bone, 
as it contains a larger quantity of decomposable ani- 
mal matter. From 500 grains of ox horn Mr. Hatch- 
ett obtained only 1-5 grains of earthy residuum, and 
not quite half of this was phosphate of lime. The 
shaving or turnings of horn form an excellent ma- 
nure, though they are not sufficiently abundant to be 
in common use. The animal matter in them seems 
to be of the nature of coagulated albumen, and it is 
slowly rendered soluble by the action of water. The 
earthy matter in horn, and still more that in bones, 
prevents the too rapid decomposition of the animal 
matter, and renders it very durable in its effects. 

Hair, woollen rags zxidi feathers are all analogous 
in composition, and principally consists of a substance 
similar to albumen, united to gelatine. This is shewn 
by the ingenious researches of Mr. Hatchett. The 
theory of their operation is similar to that of bone and 
horn shavings. 

The refuse of the different manufactures of skin 
and leather form very useful manures j such as the 



[260 J 

shavings of the currier, furriers' clippings, and the 
offals of the tan-yard and of the glue-maker. The 
gelatine contained in every kind of skin is in a state 
fitted for its gradual solution or decomposition ; and 
when buried in the soil, it lasts for a considerable 
time, and constantly affords a supply of nutritive mat- 
ter to the plants in its neighbourhood. 

Blood contains certain quantities of all the princi- 
ples found in other animal substances, and is conse- 
quently a very good manure. It has been already 
stated that it contains fibrine ; it likewise contains al- 
bumen : the red particles in it which have been sup- 
posed by many foreign chemists to be coloured by 
iron in a particular state of combination with oxygene 
and acid matter, Mr. Brande considers as formed of 
a peculiar animal substance, containing very little 
iron. 

The scum taken from the boilers of the sugar 
bakers, and which is used as manure, principally con- 
sists of bullock's blood, which has been employed for 
the purpose of separating the impurities of common 
brown sugar, by means of the coagulation of its albu- 
minous matter by the heat of the boiler. 

The different species of corals^ coraHnes, and 
sponges, must be considered as substances of animal 
origin. From the analysis of Mr. Hatchett, it appears 
that all these substances contain considerable quanti- 
ties of a matter analogous to coagulated albumen ; the 
sponges afford likewise gelatine. 

According to Merat Guillot white coral contains 
equal parts of animal matter and carbonate of lime : 



[ 261 ] 

red coral 46.5 of animal matter, and 53.5 of carbon- 
ate of lime ; articulated coraline 5 1 of animal matter, 
and 49 of carbonate of lime. 

These substances are, I believe, never used as ma- 
nure in this country, except in cases when they are ac- 
cidentally mixed with sea weed ; but it is probable that 
the coralines might be advantageously employed, as 
they are found in considerable quantity on the rocks, 
and bottoms of the rocky pools on many parts of our 
coast, where the land gradually declines towards the 
sea ; and they might be detached by hoes, and collect- 
ed without much trouble. 

Amongst excrementations, animal substances 
used as manures urine is the one upon which the 
greatest number of chemical experiments have been 
made, and the nature of which is best understood. 

The urine of the cow contains, according to the 
experiments of Mr. Brande, 

Water 65 

Phosphate of lime - - - s 

Muriates of potassa and ammonia - 15 
Sulphate of potassa . . . 6 

Carbonates, and potassa, and ammonia 4 
Urea ------ 4 

The urine of the horse, according to Fourcroy 
and Vauquelin, contains 

Of carbonate of lime 1 1 

— carbonate of soda - - - 9 
- — benzoate of soda - - - 24 

, — Muriate of potassa - - - 9 

— Urea 7 

-— Water and mucilage - - 940 



C 262 3 

In addition to these substances, Mr. Brande found 
in it phosphate of lime. 

The urine of the ass, the tamel, the rabbit, and 
domestic fowls have been submitted to different ex- 
periments, and their constitution have been found si- 
milar. In the urine of the rabbit, in addition to most 
of the ingredients above mentioned, Vauquelin detect- 
ed gelatine ; and the same chemist discovered uric 
acid in the urine of domestic fovi^ls. 

Human urine contains a greater variety of con- 
stituents than any other species examined. 

Urea, uric acid, and another acid similar to it in 
nature called rosacic acid, acetic acid, albumen, gela- 
tine, a resinous matter, and various salts are found 
in it. 

The human urine differs in composition accord- 
ing to the state of the body, and the nature of 
the food and drink made use of. In many cases 
of disease there is a much larger quantity of gelatine 
and albumen than usual in the urine j and in diabetes 
it contains sugar. 

It is probable that the urine of the same animal 
must likewise differ according to the different nature 
of the food and drink used ; and this will account for 
discordancies in some of the analyses that have been 
published on the subject. 

Urine is very liable to change and to undergo the 
putrefactive process ; and that of carnivorous animals 
more rapidly than that of graminivorous animals. In 
proportion as there is more gelatine and albumen in 
urine, so in proportion does it putrify niorfe quickly. 



C 263 -J 

The species of urine that contain most albumen, 
gelatine and urea, are the best as manures ; and all 
urine contains the essential elements of vegetables in a 
state of solution. 

Daring the putrefaction of urine the greatest 
part of the soluble animal matter that it contains is 
destroyed ; it should consequently be used as fresh 
as possible ; but if not mixed with solid matter, it 
should be diluted with water, as when pure it contains 
too large a quantity of animal matter to form a pro- 
per fluid nourishment for absorption by the roots of 
plants. 

Putrid urine abounds in ammoniacal salts ; and 
though less active than fresh urine, is a very power- 
ful manure. 

According to a recent analysis published by Ber- 
zelius, 1000 parts of urine are composed of 

Water - - - - - 9S3 

Urea - - - - - SO.l 

Uric acid - . . . 1 

Muriate of ammonia, free lactic acid,"^ 
lactate of ammonia and animal ^17.14 
matter - - - - j 

The remainder different salts, phosphates, sul- 
phates, and muriates. 

Amongst excrementitious solid substances used 
as manures, one of the most powerful is the dung of 
birds that feed on animal food, particularly the dung of 
sea birds. The guano, which is used to a great extent 
in South America, and which is the manure that fei*- 
iHizes the sterile plains of Peru, is a production of this 



[ 264 3 

kind. It exists abundantly, as we are informed by 
M. Humboldt, on the small islands in the south sea. 
at Chinche, Ilo, Iza, and Arica. 50 vessels are la- 
den with it annually at Chinche, each of which carries 
from 1500 to 2000 cubical feet. It is used a manure 
only in very small quantities ; and particularly for 
crops of maize. I made some experiments on speci- 
mens of guano sent from South America to the Board 
of Agriculture in 1 805. It appeared as a fine brown 
powder ; it blackened by heat, and gave off strong 
ammoniacal fumes ; treated with nitric acid it afford- 
ed uric acid. In 1806 M. M. Fourcroy and Vauque- 
lin published an elaborate analysis of guano. They 
state that it contains a fourth part of its weight of uric 
acid, partly saturated with ammonia, and partly with 
potassa ; some phosphoric acid combined with the 
same bases, and likewise with lime. Small quantities 
of sulphate and muriate of potassa, a little fatty matter, 
and some quartzose sand. 

It is easy to explain its fertilizing properties : 
from its composition it might be supposed to be a very 
powerful manure. It requires water for the solution 
of its soluble matter to enable it to produce its full 
beneficial effect on crops. 

The dung of sea birds has, I believe, never been 
used as a manure in this country ; but it is probable, 
that even the soil of the small islands on our coast 
much frequented by them, would fertilize. Some 
dung of sea birds brought from a rock on the coast of 
Merionethshire, produced a powerful but transient 
effect on grass. It was tried, at my request, by Sir 
Robert Vaughan at Nannau. 



[ 26.5 ] 

The rains in our climate must tend very much 
to injure this species of manure, where it is exposed 
to them, soon after its deposition ; but it may proba- 
bly be found in great perfection in caverns or clefts in. 
rocks, haunted by cormorants and gulls. I examined 
some recent cormorant's dung which I found on a 
rock near Cape Lizard in Cornwall. It had not at all 
the appearance of the guano j was of a greyish white 
colour ; had a very fcetid smell like that of putrid ani- 
mal matter : when acted on by quicklime it gave 
abundance of ammonia ; treated with nitric acid it 
yielded uric acid. 

Night soil, it is w^ell known, is a very powerful 
manure, and very hable to decompose. It differs in its 
composition ; but alw-iys abounds in substances com- 
posed of carbon, hydrogene, azote, and oxygene. 
From the analyses of Berzelius, it appears that a part 
of it is always soluble in water ; and in whatever state 
it is used, whether recent or fermented, it supplies 
abundance of food to plants. 

The disagreeable smell of night soil may be des- 
troyed by mixing it with quicklime j and if exposed to 
the atmosphere in thin layers strewed over with quick- 
lime in fine weather, it speedily dries, is easily pulver- 
ised, and in this state may be used in the same manner 
as rape cake, and delivered into the furrow with the 
seed. 

The Chinese, who have more practical know- 
ledge of the use and application of manures than any 
other people existing, mix their night soil with one- 
I third of its weight of a fat marie, make it into cakes, 

M 2 



[ 266 ] 

and dry it by exposure to the sun. These cakes, ye 
are informed by the French missionaries, have no dis- 
agreeable smell, and form a common article of com- 
merce of the empire. 

The earth, by its absorbent powers, probably 
prevents, to a certain extent, the action of moisture 
upon the dung, and likewise defends it from the ef- 
fects of air. 

After night soil, pigeons^ dung come next in or- 
der, as to fertilizing power. I digested 100 grains oi 
pigeons' dung in hot water for some hours, and ob- 
tained from it 23 grains of soluble matter ; which af- 
forded abundance of carbonate of ammonia by distil- 
lation ; and left carbonaceous matter, saline matter 
principally common salt, and carbonate of Hme as a 
residuum. Pigeons' dung when moist readily fer- 
ments, and after fermentation contains less soluble 
matter than before : from 100 parts of fermented 
pigeons' dung, I obtained only eight parts of soluble 
matter, which gave proportionally less carbonate of 
ammonia in distillation than recent pigeons' dung. 

It is evident that this manure should be applied 
as new as possible 5 and when dry, it may be employ- 
ed in the same manner as the other manures capable 
of being pulverised. 

The soil in woods where great flocks of wood- 
pigeons roost, is often highly impregnated with their 
dung-, and it cannot be doubted, would form a valuable 
manure. I have found such soil yield ammonia when 
distilled with lime. In the winter likewise it usually 
icntains abundance of vegetable matter, the remain* / 



[ 267 ] 

of decayed leaves ; and the dung tends to bring the 
vegetable matter into a state of solution. 

The dung oi domestic fozvis approaches very near- 
ly in its nature to pigeons* dung. Uric acid has been 
foufiMiin it. It gives carbonate of ammonia by distilla- 
tion, and immediately yields soluble matter to water. 
It is very liable to ferment. 

The dung of fowls is employed in common with 
that of pigeons by tanners to bring on a slight degree 
of putrefaction in skins that are to be used for making 
soft leather ; for this purpose the dung is diffused 
through water. In this state it rapidly undergoes pu- 
trefaction, and brings on a similar change in the skin. 
The excrements of dogs are employed by the tanner 
with similar effects. In all cases, the contents of the 
grainer, as the pit is called in which soft skins are pre- 
pared by dung, must form a very useful manure. 

Rabbits* dung has never been analysed. It is 
used with great success as a manure by Mr. Fane, 
who finds it profitable to keep rabbits in such a man- 
ner as to preserve their dung. It is laid on as fresh 
as possible, and is fourffl better the less it has fer- 
mented. 

The dung of cattle, oxen and cows, has been che- 
mically examined by M. M. Einhof and Thaer. They 
found that it contained matter soluble in water ; and ^ 
that it gave in fermentation nearly the same products 
as vegetable substances, absorbing oxygene and pro- 
ducing carbonic acid gas. 

The recent dung of sheep, and of deer, afford, 
when long boiled in water, soluble matters, which 



r 26S. 3 

equal from two to three per cent, of their weight. I 
have examined these soluble substances procured by 
solution and evaporation ; they contain a very small 
quantity of matter analogous to animal mucus ; and 
are principally composed of a bitter extract, soluble 
both in water and in alcohol. They give ammoniacal 
fumes by distillation ; and appear to differ very little 
in composition. 

I watered some blades of grass for several suc- 
cessive days with a solution of these extracts ; they 
evidently became greener in consequence, and grew 
more vigorously than grass in other respects, under 
the same circumstances. 

The part of the dung of cattle, sheep, and deer, 
not soluble in water, appears to be mere woody fibre, 
and precisely analogous to the residuum of those ve- 
getables that form their food after they have been de- 
prived of all their soluble materials. 

The dung of horses gives a brown fluid, which 
when evaporated, yields a bitter extract, which affords 
ammoniacal fumes more copiously than that from the 
dung of oxen. 

If the pure dung of cattle is to be used as manure 
like the other species of dung which have been men- 
tioned, there seems no reason why it should be made to 
ferment except in the soil ; or if suffered to ferment, 
it should be only in a very slight degree. The grass 
in the neighbourhood of recently voided dung, is al- 
ways coarse and dark green ; some persons have at- 
tributed this to a noxious quality in unfermented 
dung ; but it seems to be rather the result of an excess 
of food furnished to the plants. 



[ 269 ] 

The question of the proper mode of the applica* 
rion of the dung of horses and cattle, however, pro- 
perly belongs to the subject of composite manures, for 
it is usually mixed in the farm-yard with straw, offal, 
chaff, and various kind of litter; and itself contains a 
large proportion of fibrous vegetable matter. 

A slight incipient fermentation is undoubtedly of 
use in the dunghill; for by means of it a disposition is 
brought on in the woody fibre to decay and dissolve, 
when it is carried to the land, or ploughed into the 
soil; and woody fibre is always in great excess in the 
refuse of the farm. 

Too great a degree of fermentation is, however, 
very prejudicial to the composite manure in the dung- 
hill; it is better that there should be no fermentation 
at all before the manure is used, than that it should be 
carried too far. This must be obvious from what 
has been already stated in this Lecture. The excess 
of fermentation tends to the destruction and dissipa- 
tion of the most useful part of the manure; and the 
ultimate results of this process are like those of com- 
bustion. 

It is a common practice amongst farmers, to suf- 
fer the farm-yard dung to ferment till the fibrous 
texture of the vegetable matter is entirely broken 
down; and till the manure becomes perfectly cold, 
and so soft as to be easily cut by the spade. 

Independent of the general theoretical views un- 
favourable to this practice founded upon the nature 
and composition of vegetable substances, there are 
many arguments and facts which shew that it is pre^ 
judicial to the interests of the farmer. 



[ 270 ] 

During the violent fermentation which is neces- 
sary for reducing farm-yard manure to the state in 
which it is called short inuck, not only a large quantity 
of fluid, but Hkewise a gaseous matter is lost; so much 
so that the dung is reduced one half, or two-thirds in 
weight; and the principal elastic matter disengaged, is 
carbonic acid with some ammonia; and both these, if 
retained by the moisture in the soil, as has been stated 
before, are cnpable of becoming an useful nourish- 
ment of plants. 

In October, 1808, I filled a large retort capable 
of containing three pints of water, with some hot fer- 
menting manure, consisting principally of the litter 
and dung of cattle; I adapted a small receiver to the 
retort, and connected the whole with a mercurial pneu- 
matic apparatus, so as to collect the condensible and 
elastic fluids which might rise from the dung. The 
receiver soon became lined with dew, and drops be- 
gan in a few hours to trickle down the sides of it. 
Elastic fluid likewise was generated; in three days S5 
cubical inches had been formed, which when analy- 
sed, were found to contain 21 cubical inches of car- 
bonic acid, the remainder was hydrocarbonate mixed 
with some azote, probably no more than existed in 
the common air in the receiver. The fluid matter 
collected in the receiver at the same time amounted 
to nearly half an ounce. It had a saline taste, and a 
disagreeable smell, and contained some acetate and 
carbonate of ammonia. 

Finding such products given ofl:' from ferment- 
ing litter, I introduced the beak of another retort 



C 271 ] 

filled with similar dung very hot at the time, into 
the soil amongst the roots of some grass in the bor- 
der of a garden; in less than a week a very distinct et- 
fect was produced upon the grass; upon the^ spot 
exposed to the influence of the matter disenga- 
ged in fermentation, it grew with much more lux- 
uriance than the grass in any other part of the gar- 
den. 

Besides the dissipation of gaseous matter- when 
fermentation is pushed to the extreme, there is ano- 
ther disadvantage in the loss oi heat, which, if excited 
in the soil, is useful in promoting the germination of 
the seed, and in assisting the plant in the first stage of 
its growth, when it is most feeble and most liable to 
disease: and the fermentation of manure in the soil 
must be particularly favourable to the wheat crop in 
preserving a genial temperature beneath the surface 
late in autumn, and during winter. 

Again, it is a general principal in chemistry, that 
in all cases of decomposition, substances combine 
much more readily at the moment of their disengage- 
ment, than after they have been perfectly form.ed. — 
And in fermentation beneath the soil the fluid matter 
produced is applied instantly, even whilst it is warm, 
to the organs of the plant, and consequently is more 
likely to be efficient, than in manure that has gone 
through the process; and of which all the principles 
have entered into new combinations. 

In the writings of scientific agriculturists, a great 
mass of facts may be found in favour of the applica- 
tion of farm-yard dung in a recent state. Mr. Young, 
in the Essay on Manures, which I have already quoted. 



t 272 ] 

adduces a number of excellent authorities in support 
of the plan. Many who doubted, have been lately con- 
vinced; and perhaps there is no subject of investiga- 
tion in which there is such a union of theoretical and 
practical evidence. I have myself within the last ten 
years witnessed a number of distinct proofs on the 
subject. I shall content myself with quoting that 
which ought to have, and which I am sure will have, 
the greatest weight amongst agriculturists. Within 
the last seven years Mr. Coke has entirely given up 
the system formerly adopted on his farm of applying 
fermented dung; and he informs me, that his crops 
have been since as good as they ever were, and that 
his manure goes nearly twice as far. 

A great objection against slightly fermented dung 
is, that weeds spring up more luxuriantly where it is 
applied. If there are seeds carried out in the dung 
they certainly will germinate; but it is seldom that this 
can be the case to any extent; and if the land is not 
cleansed of weeds, any kind of manure fermented or 
unfermented will occasion their rapid growth. If 
slightly fermented farm-yard dung is used as a top 
dressing for pastures, the long straws and unfermented 
vegetable matter remaining on the surface should be 
removed as soon as the grass begins to rise vigorous- 
ly by raking, and carried back to the dunghill: in this 
case no manure will be lost, and the husbandry will 
be at once clean and ceconomical. 

In cases when farm-yard dung cannot be immedi- 
ately applied to crops, the destructive fermentation of 
it should be prevented as much as posssible: the prin- 



C 273 ] 

ciples on which this may be effected have been allud- 
ed to. 

The surface should be defended as much as poi- 
sible from the oxygene of the atmosphere ; a compact 
marie, or a tenacious clay, offers the best protection 
against the air ; and before the dung is covered over, 
or as it were, sealed up, it should be dried as much 
as possible. If the dung is found at any time to 
heat strongly, it should be turned over, and cooled 
by exposure to air. 

Watering dunghills is sometimes recommended 
for checking the progress of fermentation ; but this 
practice is inconsistent with just chemical views. It 
may cool the dung for a short time ; but moisture, as 
I have before stated, is a principal agent in all proces- 
ses of decomposition. Dry fibrous matter will never 
ferment. Water is as necessary as air to the process ; 
and to supply it to fermenting dung, is to supply an 
agent which will hasten its decay. 

In all cases when dung is fermenting, there are 
simple tests by which the rapidity of the process, and 
consequently the injury done, may be discovered. 

If a thermometer plunged into the dung does not 
rise to above 100° degrees of Fahrenheit, there is little 
.danger of much aeriform matter flying off. If the 
temperature is higher, the dung should be immediate- 
ly spread abroad. 

When a piece of paper moistened in muriatic 
acid held over the steams arising from a dunghill 
gives dense fumes, it is a certain test, that the decom- 

N 9. 



1. 274 ] 

position is going too far ; for this indicates that vola- 
tile alkali is disengaged. 

When dung is to be preserved for any time, the 
situation in which it is kept is of importance. It 
should, if possible, be defended from the sun. To 
preserve it under sheds would be of great use ; or to 
make the site ®f a dunghill on the north side of a wall. 
The floor on which the dung is heaped, should, if pos- 
sible, be paved with flat stones ; and there should be 
a little inclination from each side towards the centre, 
in which there should be drains connected with a 
small well furnished with a pump, by which any fluid 
matter may be collected for the use of the land. It 
too often happens that a dense mucilaginous and ex- 
tractive fluid is suffered to drain away from the dung- 
hill, so as to be entirely lost to the farm. 

Street and road dung, and the siveepings of houses 
may be all regarded as composite manures, the con- 
stitution of them is necessarily various, as they are 
derived from a number of different substances. These 
manures are usually applied in a proper manner, with- 
out being fermented. 

Soot, which is principally formed from the com- 
bustion of pit coal or coal, generally contains likewise 
substances derived from animal matters. This is a 
very powerful manure. It affords ammoniacal salts 
by distillation, and yields a brown extract to hot wa- 
ter, of a bitter taste. It likewise contains an empy- 
reumatic oil. Its great basis is charcoal, in a state in 
which it is capable of being rendered soluble by the 
action of oxygene and water. 



[ 275 ] 

This manure is well fitted to be used in the dry 
state, thrown into the ground with the seed, and re- 
quires no preparation. 

The doctrine of the proper application of ma- 
nures from organized substances, offers an illustration 
of an important part of the oeconomy of nature, and 
of the happy order in which it is arranged. 

The death and decay of animal substances tend 
to resolve organised forms into chemical constituents ; 
and the pernicious effluvia disengaged in the process 
seem to point out the propriety of burying them in 
the soil, where they are fitted to become the food of 
vegetables. The fermentation and putrefaction of or- 
ganised substances in the free atmosphere are noxious 
processes ; beneath the surface of the ground they 
are salutary operations. In this case the food of plants 
is prepared where it can be used ; and that which 
would offend the senses and injure the health, if ex- 
posed, is converted by gradual processes into forms of 
beauty and of usefulness ; the foetid gas is rendered a 
constituent of the aroma of the flower, and what 
might be poison, becomes nourishment to animals 
and to man. 



[ ^7tJ 3 



LECTURE VIL 

On Manures of mineral Origin, or fossile Manures ; 
their Preparation, and the Manner in 'which they 
Act. Of Lime in its different States ; Operation of 
Lime as a Manure and a Cement ; different Combin- 
ations of Lime. Of Gypsum ; Ideas respecting its 
Use. Of other Neutro-saline Compounds , employed as 
Manures. Of Alkalies and alkaline Salts ; of Com- 
mon Salt. 

THE whole tenor of the preceding Lectures 
shews, that a great variety of substances contributes 
to the growth of plants, and supplies the materials of 
their nourishment. The conversion of matter that 
has belonged to living structures into organised 
forms, is a process that can be easily understood ; but 
it is more difficult to follow those operations by which 
earthy and saline matters are consolidated in the fibre 
of plants, and by which they are made subservient to 
their functions. Some enquirers adopting that sublime 
generalization of the ancient philosophers, that matter 
is the same in essence, and that the different substan- 
ces considered as elements by chemists, are merely 
different arrangements of the same indestructible par- 
ticles, have endeavoured to prove that all the varieties 
of the principles found in plants, may be formed from 



[ 277 ] 

the substances in the atmosphere ; and that vegetable 
life is a process in which bodies that the analytical phi- 
losopher is unable to change or to form, are constantly 
composed and decomposed. These opinions have not 
been advanced merely as hypotheses; attempts have 
been made to support them by experiments. M. 
Schrader and Mr. Braconnot, from a series of distinct 
investigations, have arrived at the same conclusions. 
They state that different seeds sown in fine sand, sul- 
phur, and metallic oxides, and supplied only with 
atmospherical air and water, produced healthy plants, 
which by analysis yielded various earthy and saline 
matters, which either were not contained in the seeds, 
or the material in which they grew; or which were 
contained only in much smaller quantities in the seeds: 
and hence they conclude that they must have been 
formed from air or water, in consequence of the agen- 
cies of the living organs of the plant. • 

The researches of these two gentlemen were con- 
ducted with much ingenuity and address; but there 
were circumstances which interfered with their re- 
sults, which they could not have known, as at the 
time their labours were published they had not been 
investigated. 

I have found that common distilled water is far 
from being free from saline impregnations. In analy- 
sing it by Voltaic electricity, I procured from it alkal- 
ies and earths; and many of the combinations of me- 
tals with chlorine are extremely volatile substances.— 
When distilled water is supplied in an unlimited man- 
ner to plants, it may furnish to them a number of dif- 



[ 278 ] 

feretit substances, which though in quantities scarcely 
perceptible in the water, may accumulate in the plant, 
■which probably perspires only absolutely pure water. 

In 1801 I made an experiment on the growth of 
oats, supplied with a limited quantity of distilled wa- 
ter in a soil composed of pure carbonate of lime. The 
soil and the water were placed in a vessel of iron, ' 
which was included in a large jar, connected with the 
free atmosphere by a tube, so curved as to prevent the ' 
possibility of any dust, or fluid, or solid matter from 
entering into the jar. My object was to ascertain 
whether any siliceous earth would be formed in the 
process of vegetation; but the oats grew very feebly, 
and began to be yellow before any flowers formed: 
the entire plants were burnt, and their ashes compar- 
ed with those from an equal number of grains of oat. 
Less siliceous earth was given by the plants than by 
the grains; but their ashes yielded much more carbon- 
ate of Hme. That there was less siliceous earth I 
attribute to the circumstance of the husk of the oat be- 
ing thrown off in germination; and this is the part 
which most abounds in silica. Healthy green oats ta- 
ken from a growing crop, in a field of which the soil 
was a fine sand, yielded siliceous earth in a much 
greater proportion than an equal weight of the corn 
artificially raised. 

The general results of this experiment are very 
much opposed to the idea of the composition of the 
earths, by plants, from any of the elements found in 
the atmosphere, or in water; and there are other facts 
contrary to the idea. Jacquin states that the ashes of 



Glass Wort (Salsola Soda, J when it grows in inland 
situations, afford the vegetable alkali; when it grows 
on the sea shore where compounds which afford the 
fossile or marine alkali are more abundant, it yields 
that substance. Du Hamel found, that plants which 
visually grow on the sea shore, made small progress 
when planted in soils containing little common salt. 
The sunflower, when growing in lands containing no 
nitre, does not afford that substance; though when 
watered by a solution of nitre, it yields nitre abundant- 
ly. The tables of de Saussure, referred to in the 
Third Lecture, shew that the ashes of plants are simi- 
lar in constitution to the soils in which they have 
vegetated. 

De Saussure made plants grow in solutions of 
different salts, and he ascertained, that in all cases, 
certain portions of the salts were absorbed by the 
plant and found unaltered in their organs. 

Even animals do not appear to possess the 
power of forming the alkaline and earthy substan- 
ces. Dr. Fordyce found, that when canary birds 
at the time they were laying eggs were deprived of 
access to carbonate of lime, their eggs had soft shells; 
and if there is any process for which nature may be 
conceived most likely to supply resources of this kind, 
it is that connected with the reproduction of the spe- 
cies. 

As the evidence on the subject now stands, it 
seems fair to conclude that the different earths and 
saline substances found in the organs of plants, are 
?=upplied by the soils in which they grow; and in nc 



C 280 ] 

cases composed by new arrangements of the elements 
in air or water. AVhat may be our ultimate view of 
the laws of chemistry, or how far our ideas of element- 
ary principles may be simplified, it is impossible to say. 
We can only reason from facts. We cannot imitate 
the powers of composition belonging to vegetable 
structures; but at least we can understand them: and 
as far as our researches have gone, it appears that in 
vegetation compound forms are uniformly produced 
from simpler ones; and elements in the soil, the at- 
mosphere, and the earth absorbed and made parts of 
beautiful diversified structures. 

The views which have been just developed lead 
to correct ideas of the operation of these manures 
which are not necessarily the result of decayed organi- 
zed bodies, and which are not composed of different 
proportions of carbon, hydrogene, oxygene and azote. 
— They must produce their effect, either by becom- 
ing a constituent part of the plant, or by acting upon 
its more essential food, so as to render it more fitted 
for the purposes of vegetable life. 

The only substances which can with propriety be 
called fossils manures, and which are found unmixed 
with the remains of any organized beings, are certain 
alkaline earths or alkahes, and their combinations. 

The only alkaHne earths which have been hither- 
to applied in this way, are lime and magnesia. Potassa 
and soda, the two fixed alkalies, are both used in 
certain of their chemical compounds. I shall state in 
succession such facts as have come to my knowledge 
respecting each of these bodies in their applications to 



[ 281 ] 

the purposes of agriculture j but I shall enlarge most 
upon the subject of lime ; and if I should enter into 
some details which may be tedious and minute, I trust, 
my excuse will be found in the importance of the en- 
quiry ; and it is one which has been greatly elucidated 
by late discoveries. 

The most common form in which lime is found 
on the surface of the earth, is in a state of combination 
with carbonic acid or fixed air. If a piece of lime- 
stone, or chalk, be thrown into a fluid acid, there will 
be an effervescence. This is owing to the escape of 
the carbonic acid gas. The hme becomes dissolved 
in the liquor. 

When limestone is strongly heated, the car- 
bonic acid gas is expelled, and then nothing remains 
but the pure alkaline earth ; in this case there is a loss 
of weight ; and of if the fire has been very high, it 
approaches to one-half the weight of the stone j but 
in common cases limestones, if well dried before burn- 
ing, do not lose much more than from 35 to 40 per 
cent., or from seven to eight parts out of 20. 

I mentioned in discussing the agencies of the at- 
mosphere upon vegetables, in the beginning of the Fifth 
Lecture, that air always contains carbonic acid gas, and 
that lime is precipitated from water by this substance. 
When burnt lime is exposed to the atmosphere, in a 
certain time it becomes mild and is the same substance 
as that precipitated from lime water ; it is combined 
with carbonic acid gas. Quicklime; when first made, 
is caustic and burning to the tongue, renders vegetable 
blues green, and is soluble in water j but when com- 

o 2 



C 282 3 

billed with carbonic acid it loses all these properties, 
its solubility and its taste : it regains its power of ef- 
fervescing, and becomes the same chemical substance 
as chalk or limestone. 

Very few limestones or chalks consist entirely of 
lime and carbonic acid. The statuary marbles, or 
certain of the rhomboidal spars, are almost the only 
pure species ; and the different properties of limestone 
both as manures and cements, depend upon the nature 
of the ingredients mixed in the limestone ; for the 
true calcareous element, the carbonate of lime, is uni- 
formly the same in nature, properties and effects, and 
consist of one proportion of carbonic acid 41,4, and 
one of lime 55. 

When a limestone does not copiously effervesce 
in acids, and is sufficiently hard to scratch glass, it 
contains silicious and probably aluminous earth. 
When it is deep brown or red, or strongly coloured 
of any of the shades of brown or yellow, it contains 
oxide of iron. When it is not sufficiently hard to 
scratch glass, but effervesces slowly, and makes the 
acid in which it effervesces milky, it contains mag- 
nesia. And when it is black and emits a foetid smell 
if rubbed, it contains coally or bituminous matter. 

The analysis of limestones is not a difficult mat- 
ter j and the proportions of their constituent parts 
may be easily ascertained, by the processes described 
in the Lecture on the Analysis of Soils ; and usually 
with sufficient accuracy for all the purposes of the 
farmer, by the fifth process. 

Before any opinion can be formed of the man- 
ner in which the different ingredients in limestones 



[ 283 ] 

modify their properties, it will be necessary to consi- 
der the operation of the pure calcareous element as a 
manure, and as a cement. 

Quicklime in its pure state, whether in powder 
or dissolved in water, is injurious to plants. — I have 
in several instances killed grass by watering it with 
lime water. — But lime in its state of combination with 
carbonic acid, as is evident from the analyses given in 
the Fourth Lecture, is a useful ingredient in soils. 
Calcareous earth is found in the ashes of the greater 
number of plants ; and, exposed to the air, lime can- 
not long continue caustic, for the reasons that were 
just now assigned ; but soon becomes united to car- 
bonic acid. 

When newly burnt lime is exposed to air, it soon 
falls into powder ; in this case it it called slacked 
lime ; and the same effect is immediately produced 
by throwing water upon it, when it heats violently, 
and the water disappears. 

Slacked lime is merely a combination of lime, 
with about one-third of its weight of water ; i. e. 55 
parts of lime absorb 17 parts of water; and in this 
case it is composed of a definite proportion of lime to 
a definite proportion of water, and is called by che- 
mists hydrate of lime ; and when hydrate of lime be- 
comes carbonate of lime by long exposure to air, the 
water is expelled, and the carbonic acid gas takes its 
place. 

When lime, whether freshly burnt or slacked, is 

' mixed with any moist fibrous vegetable matter, there 

is a strong action between the lime and the vegetable 



[ 284 3 

matter, and they form a kind of compost together, 
of which a part is usually soluble in water. 

By this kind of operation, lime renders matter 
which was before comparatively inert, nutritive ; and 
as charcoal and oxygene abound in all vegetable mat- 
ters, it becomes at the same time converted into car- 
bonate of lime. 

Mild lime, powdered limestone, marles or chalks, 
have no action of this kind upon vegetable matter ; 
by their action they prevent the too rapid decomposi- 
tion of substances already dissolved ; but they have no 
tendency to form soluble matters. 

It is obvious from these circumstances, that the 
operation of quicklime, and marie or chalk, depends 
upon principles altogether different. — Quicklime in 
being applied to land tends to bring any hard vegeta- 
ble matter that it contains into a state of more rapid 
decomposition and solution, so as to render it a pro- 
per food for plants. — Chalk, and marie, or carbonate 
of lime will only improve the texture of the soil, or 
its relation to absorption ; it acts merely as one of its 
earthy ingredients. — ^Quicklime, when it becomes 
mild, operates in the same manner as chalk ; but in 
the act of becoming mild, it prepares soluble out of 
insoluble matter. 

It is upon this circumstance that the operation of 
Ijme in the preparation for wheat crops depends ; and 
its efficacy in fertilizing peats, and in bringing into a 
state of cultivation all soils abounding in hard roots, 
or dry fibres, or inert vegetable matter. 

The solution of the question whether quicklime 
ought to be applied to a soil, depends upon the quan. 



[ 285 ] , 

tity of inert vegetable matter that it contains. The 
solution of the question whether marie, mild lime, or 
powdered limestone ought to be applied, depends upon 
the quantity of calcareous matter already in the soil. 
All soils are improved by mild lime, and ultimately 
by quicklime which do not effervesce wi[h acids ; and 
sands more than clays. 

When a soil deficient in calcareous matter contains 
much soluble vegetable manure, the appHcation of 
quicklime should always be avoided, as it either tends 
to decompose the soluble matters by uniting to their 
carbon and oxygene so as to become mild lime, or it 
combines with the soluble matters, and forms com- 
pounds having less attraction for water than the pure 
vegetable substance. 

The case is the same with respect to most animal 
manures; but the operation of the lime is different in dif- 
ferent cases, and depends upon the nature of the animal 
matter. Lime forms a kind of insoluble soap with oily 
matters, and then gradually decomposes them by se- 
parating from them oxygene and carbon. It combines 
likewise with the animal acids ; and probably assists 
their decomposition by abstracting carbonaceous mat- 
ter from them combined with oxygene ; and conse- 
quently it must render them less nutritive. It tends to 
diminish likewise the nutritive powers of albumen from 
the same causes ; and always destroys to a certain 
extent the efficacy of animal manures, either by com- 
bining with certain of their elements, or by giving to 
them new arrangements. Lime should never be ap- 
plied with animal manures, unless they are too rich, 



[ 286 3 

or for the purpose of preventing noxious effluvia, as 
in certain cases mentioned in the last Lecture. It is 
injurious when mixed v^^ith any common dung, and 
tends to render the extractive matter insoluble. 

I made an experiment on this subject : I mixed 
a quantity of the brown soluble extract, which was 
procured from sheeps' dung with five times its weight 
of quicklime. I then moistened them with water ; 
the mixture heated very much ; it was suffered to re- 
main for 14 hours, and was then acted on by six or 
seven times its bulk, of pure water : the water, after 
being passed through a filter, was evaporated to dry- 
ness ; the solid matter obtained was scarcely coloured, 
and was lime mixed with a little saline matter. 

In those cases in which fermentation is useful to 
produce nutriment from vegetable substances, lime is 
always efficacious. I mixed some moist tanner's spent 
bark with one-fifth of its weight of quicklime, and suf- 
fered them to remain together in a close vessel for 
three months ; the lime had become coloured and was 
effervescent : when water was boiled upon the mix- 
ture it gained a tint of fawn colour, and by evapora- 
tion furnished a fawn-coloured powder, which must 
have consisted of lime united to vegetable matter, for 
it burnt when stongly heated and left a residuum of 
mild lime. 

The limestones containing alumina and silica are 
less fitted for the purposes of manure than pure lime- 
stones ; but the hme formed from them has no nox- 
ious quality. Such stones are less efficacious, merely 
because they furnish a smaller quantity of quicklime. 



[ 287 ] 

I mentioned bituminous limestones. There is 
very seldom any considerable portion of coally inatter 
in these stones ; never as much as five parts in 100 ; 
but such limestones make very good hme. The car- 
bonaceous matter can do no injury to the land, and 
may, under certain circumstances, become a food of 
the plant, as is evident from what was stated in the 
last Lecture. 

The subject of the application of the magnesian 
limestone is one of great interest. 

It had been long known to farmers in the neigh- 
bourhood of Doncaster, that hme made from a certain 
limestone applied to the land, often injured the crops 
considerably, as I mentioned in the Introductory Lec- 
ture. Mr. Tennant, in making a series of experi- 
ments upon this peculiar calcareous substance, found 
that it contained magnesia ; and on mixing some cal- 
cined magnesia with soil, in which he sowed different 
seeds, he found that they either died, or vegetated in 
a very imperfect manner, and the plants were never 
healthy. And with great justice and ingenuity he re- 
ferred the bad effects of the peculiar limestone to the 
magnesian earth it contains. 

In making some enquiries concerning this sub- 
ject, I found that there were cases in which this mag- 
nesian limestone was used with good effect. 

Amongst some specimens of limestone which 
Lord Somerville put into my hands, two marked as 
peculiarly good proved to be magnesian limestones. 
And lime made from the Breedon limestone is used in 
Leicestershire, where it is called hot lime ; and I have 



[ 288 j 

been inforriied by farmers in the neighbourhood of the \ 
quarry, that they employ it advantageously in small ; 
quantities, seldom more than 25 or 30 bushels to the I 
acre. And that they find it may be used with good 
effect in larger quantities upon rich land. 

A minute chemical consideration of this question 
will lead to its solution. 

Magnesia has a much weaker attraction for car- 
bonic acid than lime, and will remain in the state of ■ 
caustic or calcined magnesia for many months, though ; 
exposed to the air. And as long as any caustic lime ' 
remains, the magnesia cannot be combined with car- 
bonic acid, for lime instantly attracts carbonic acid \ 
from magnesia. 

When a magnesian limestone is burnt, the mag- 
nesia is deprived of carbonic acid much sooner than 
the lime ; and if there is not much vegetable or ani- 
mal matter in the soil to supply by its decomposition 
carbonic acid, the magnesia will remain for a long 
while in the caustic state ; and in this state acts as a 
poison to certain vegetables. And that more magne- 
sian lime may be used upon rich soils, seems to be 
owing to the circumstance, that the decomposition of 
the manure in them supplies carbonic acid. And 
magnesia in its mild state, i. e. fully combined with 
carbonic acid, seems to be always an useful constituent 
of soils. I have thrown carbonate of magnesia (pro- 
cured by boiling the solution of magnesia in super- 
carbonate of potassa) upon grass, and upon growing 
wheat and barley, so as to render the surface white ; 
but the vegetation was not injured in the slightest de- 



t 289 ] 

gree. And one of the most fertile parts of Cornwaii, 
the Lizard, is a district in which the soil contains 
mild magnesian earth. 

The Lizard Downs bear a short and green grass, 
which feeds sheep producing excellent mutton j and 
the cultivated parts are amongst the best corn lands in 
the county. 

That the theory which I have ventured to give of 
the operation of magnesian lime is not unfounded, is 
shewn by an experiment which I made expressly for 
the purpose of determining the true nature of the 
operation of this substance. I took four portions of 
the same soil : with one I mixed -20 of its weight of 
caustic magnesia, with another I mixed the same 
quantity of magnesia and a proportion of a fat decom- 
posing peat equal to one-fourth of the weight of the 
soil. One portion of soil remained in its natural 
state : and another was mixed with peat without mag- 
nesia. The mixtures were made in December 1 806 ; 
and in April 1807, barley was sown in all of them. 
It grew very well in the pure soil ; but better in the 
soil containing the magnesia and peat ; and nearly as 
well in the soil containing peat alone : but in the soil 
containing the magnesia alone, it rose very feeble, and 
looked yellow and sickly. 

I repeated this experiment in the summer of 1 8 10 
with similar results ; and I found that the magnesia 
in the soil mixed with peat became strongly efferves- 
cent, whilst the portion in the unmixed soil gave car- 
bonic acid in much smaller quantities. In the one case 
the magnesia had assisted in the formation of a man- 

p 2 



[ 290 ] 

ure, and had become mild ; in the otner case it had 
acted as a poison. 

It is obvious from what has been said that lime 
from the magnesian limestone may be applied in large 
quantities to peats; and that where lands have been 
injured by the application of too large a quantity of 
magnesian lime, peat will be a proper and efficient 
remedy. 

I mentioned that magnesian lime stones efferves- 
ced little when plunged into an acid. A simple test 
of magnesia in a limestone is this circumstance, in its 
rendering diluted nitric acid, or acqua fortis milky. 

From the analysis of Mr. Tennant, it appears 
that the magnesian limestones contain from 
20.3 to 22.5 magnesia. 
29.5 to 31.7 lime. 
47.2 carbonic acid. 
0.8 clay and oxide of iron. 

Magnesian hmestones are usually coloured brown.' 
or pale yellow, they are found in Somersetshire, Lei-* 
cestershire, Derbyshire, Shropshire, Durham, and 
Yorkshire. I have never met with any in other coun- 
ties in England; but they abound in many parts of 
Ireland, particularly near Belfast. 

The use of lime as a cement is not a proper sub- 
ject for extensive discussion in a course of Lectures on 
the chemistry of agriculture; yet as the theory of the 
operation of lime in this way is not fully stated in any 
elementary book that I have perused, I shall say a 
very few words on the applications of this part of che- 
mical knowledge. 



r 291 



There are two modes in which lime acts as a ce* 
ment; in its combination with water, and in its combi- 
nation with carbonic acid. 

Ihe hydrate of lime has been ah*eady mentioned^ 
When quick, lime is rapidly made into a paste with 
water, it soon loses its softness, and the water and the 
lime form together a solid coherent mass, which con- 
sists, as has been stated before, of 1 7 parts of water to 
55 parts of lime. When hydrate of lime whilst it is 
consolidating is mixed with red oxide of iron, alumina, 
or silica, the mixture becomes harder and more co- 
herent than when lime alone is used; and it appears 
that this is owing to a certain degree of chemical at- 
traction between hydrate of lime and these bodies; and 
they render it less liable to decompose by the action 
of the carbonic acid in the air, and less soluble in 
water. 

The basis of all cements that are used for 
works which are to be covered with water must be 
formed from hydrate of lime; and the lime made from 
impure limestones answers this purpose very well. 
Puzzolana is composed principally oi silica, alumina, 
and oxide of iron; and it is used mixed with lime to 
form cements intended to be employed under water. 
Mr. Smeaton, in the construction of the Eddystone 
light house, used a cement comp©sed of equal parts by 
weight of slacked lime and puzzolana. Puzzolana is 
a decomposed lava. Tarras, which was formerly im- 
ported in considerable quantities from Holland, is a 
mere decomposed basalt: two parts of slacked lime and 
one part of tarras forms the principal part ofthe raor- 



[ 292 3 

tar used in the great dykes of Holland. Substance? 
which will answer all the ends of puzzolana and tar • 
ras are abundant in the British islands. An excellent 
red tarras may be procured in any quantities from the 
Giants' Causeway in the north of Ireland: and decom- 
posing basalt is abundant in many parts of Scotland, 
and in the northern districts of England in which coal 
is found. 

Parker's cement, and cements of the same kind 
made at the alum works of Lord Dundas and Lord 
Mulgrave are mixtures of calcined ferruginous stones, 
with hydrate of lime. 

The cements which act by combining with car- 
bonic acid, or the common mortars, are made by mix- 
ing together slacked lime and sand. These mortars, 
at first solidify as hydrates, and are slowly converted 
into carbonate of lime by the action of the carbonic 
acid of the air. Mr. Tennant. found that a mortar of 
this kind in three years and a quarter had regained 63 
per cent, of the quantity of carbonic gas which con- 
i^titutes the definite proportion in carbonate of lime. 
The rubbish of mortar from houses owes its power to 
benefit lands principally to the carbonate of lime it 
contains; and the sand in it; and its state of cohesion 
renders it particularly fitted to improve clayey soils. 

The hardness of the mortar in very old buildings 
depends upon the perfect conversion of all its parts 
into carbonate of lime. The purest limestones are the 
best adapted for making this kind of mortar; the mag- 
nesian limestones make excellent water cements; but 
act with too /ittle energy upon carbonic acid gas to 
make good common morter. 



[ 293 J 

The Romans, according to Pliny, made their 
best mortar a year before it was usedj so that it was 
partially combined with carbonic acid gas before it 
was employed. 

In burning lime there are some particular pre- 
cautions required for the different kinds of limestones. 
In general, one bushel of coal is sufficient to make 
four or five bushels of lime. The magnesian lime- 
stone requires less fuel than the common limestone. 
In all cases in which a limestone containing much alu- 
minous or siliceous earth is burnt, great care should 
be taken to prevent the fire from becoming too intense; 
for such lime easily virtrifies, in consequence of the 
affinity of lime for silica and alumina. And as in some 
places there are no other limestones than such as con- 
tain other earths, it is important to attend to this cir- 
cumstance. A moderately good lime may be made at 
a low red heat; but it will melt into a glass at a white 
heat. In limekilns for burning such lime, there 
should be always a damper. 

In general, when limestones are not magnesian 
their purity will be indicated by their loss of weight 
in burning; the more they lose the larger is the quan- 
tity of calcareous matter they contain. The magne- 
sian limestones contain more carbonic acid than the 
common limestones; and I have found all of them lose 
more than half their weight by calcination. 

Besides being used in the forms of lime and carbon- 
ate of lime, calcareous matter is applied for the pur- 
poses of agriculture in other combinations. One of 
these bodies is gypsum or sulphate of lime. This sub- 



[ 294 J 

stance consists of sulphuric acid (the same body that 
exists combined with water in oil of vitriol) and lime; 
and when dry it is composed of 55 parts of lime and 75 
parts of sulphuric acid. Common gypsum or selenite, 
such as that found at Shotover hill near Oxford, con- 
tains besides sulphuric acid and lime, a considerable 
quantity of water ; and its composition may be thus 
expressed : 

Sulphuric acid one proportion 75 

Lime one proportion - - 55 
Water two proportions - - St 

The nature of gypsum is easily demonstrated ; 
if oil of vitriol be added to quicklime there is a violent 
heat produced ; when the mixture is ignited, water is 
given off, and gypsum alone is the result, if the acid 
has been used in sufficient quantity ; and gypsum 
mixed with quicklime, if the quantity has been defi- 
cient. Gypsum free from water is sometimes found 
in nature, when it is called anhydrous selenite. ^ It is 
distinguished from common gypsum by giving off no 
•water when heated. 

When gypsum free from water, or deprived of 
water by heat, is made into a paste with water, it ra- 
pidly sets by combining with that fluid. Plaister of 
Paris is powdered dry gypsumj and its property as a 
cement, and in its use in making casts depends upon 
its solidifying a certain quantity of water, and making 
with it a coherent mass. Gypsum is soluble in about 
.500 times its weight of cold water, and is more solu- 
ble in hot water ; so that when water has been boiled 
in contact with gypsum, crystals of this substance are 



t 295 3 

deposited as the water cools. Gypsum is easily dis- 
tinguished when dissolved by its properties of afford* 
ing precipitates to solutions of oxalates and of barytic 
salts. 

Great difference of opinion has prevailed amongst 
agriculturists with respect to the uses of gypsum. It 
has been advantageously used in Kent, and various 
testimonies in favour of its efficacy have been laid be- 
fore the Board of Agriculture by Mr. Smith. In 
America it is employed with signal success ; but in 
most counties of England it has failed, though tried 
in various ways, and upon different crops. 

Very discordant notions have been formed as to 
the mode of operation of gypsum. It has been sup- 
posed by some persons to act by its power of attract- 
ing moisture from the air ; but this agency must be 
comparatively insignificant. When combined with wa- 
ter it retains that fluid too powerfully to yield it to the 
roots of the plant, and its adhesive attraction for mois- 
ture is inconsiderable ; the small quantity in which it 
is used likewise is a circumstance hostile to this idea. 

It has been said that gypsum assists the putrefac- 
tion of animal substances, and the decomposition of 
manure. I have tried some experiments on this subject 
which are contradictory to the notion, I mixed some 
minced veal with about ih part of its weight of gyp- 
sum, and exposed some veal without gypsum under 
the same circumstances : there was no difference in 
the time in which they began to putrefy ; and the pro- 
cess seemed to me most rapid in the case in which there 
was no gypsum present, I made other similar mix- 



[ 296 ] 

tures, employing in some cases larger, and in some 
cases smaller quantities of gypsum j and I used 
pigeons' dung in one instance instead of flesh, and 
with precisely similar results. It certainly in no case 
increased the rapidity of putrefaction. 

Though it is not generally known, yet a series of 
experiments has been carried on for a great length of 
time in this country upon the operation of gypsum as 
a manure. The Beikshire and the Wiltshire peat- 
ashes contain a considerable portion of this substance. 
In the Newbury peat-ashes I have found from one 
fourth to one-third of gypsum ; and a larger quantity 
in some peat-ashes from the neighbourhood of Stock- 
bridge : the other constituents of these ashes are cal- 
careous, aluminous, and siliceous earth, with variable 
quantities of sulphate ofpotassa, a little common salt, 
and sometimes oxide of iron. The red ashes contain 
most of this last substance. 

These peat-ashes are used as a top dressing for 
cultivated grasses, particularly sainfoin and clover. 
In examining the ashes of sainfoin, clover, and rye 
grass, I found that they afforded considerable quanti- 
ties of gypsum ; and this substance, probably, is inti* 
mately combined as a necessary part of their woody 
fibre. If this be allowed, it is easy to explain the rea- 
son why it operates in such small quantities j for the 
whole of a clover crop, or sainfoin crop, on an acre, 
according to my estimation, would afford by incinera- 
tion only three or four bushels of gypsum. In exam- 
ining the soil in a field near Newbury, which was ta- 
ken from belov/ a foot-path near the gate, where gyp- 



L 297 J 

sum could not have been artificially furnished, I couiJ 
not detect any of this substance in it; and at the very 
time I collected the soil, the peat-ashes were applied 
to the clover in the field. The reason why gypsum is 
not generally efficacious is probably because most 
cultivated soils contain it in sufficient quantities for the 
use of the grasps. In the common course of cultiva- 
tion, gypsum is furnished in the manure; for it is con- 
tained in stable dung, and in the dung of all cattle fed 
on grass; and it is not taken up in corn crops, or crops 
of peas and beans, and in very small quantities in 
turnip crops; but where lands are exclusively devoted 
to pasturage and hay, it will be continually consumed. 
I have examined, four different soils cultivated by a 
series of common courses of crops, for gypsum. One 
was a light sand from Norfolk; another a clay bearing 
good wheat from Middlesex; the third a sand from 
Sussex; the fourth a clay from Essex. I found gyp- 
sum in all of them; and in the Middlesex soil it amount- 
ed nearly to one per cent. Lord Dundas informs me, 
that having tried gypsum without any benefit on two 
of his estates in Yorkshire, he was induced to have 
the soil examined for gypsum according to the pro« 
cess described in the Fourth Lecture, and this sub- 
stance was found in both the soils. 

Should these statements be confirmed by future 
enquirers, a practical inference of some value may be 
derived from them. It is possible that lands which 
have ceased to bear good crops of clover, or artificial 
grasses, may be restored by being manured with gyp- 
sum. I have mentioned that this substance is found 

Q2 



[ 298 ] 

m Oxfordshire; it is likewise abundant in many other 
parts of England; in Gloucestershir,e, Somersetshire. 
Derbyshire, Yorkshire, &c. and requires only pulveri- 
zation for its preparation. 

Some very interesting documents upon the use of 
sulphate of iron or green vitriol, which is a salt pro- 
duced from peat in Bedfordshire, ha^e been laid be- 
fore the Board by Dr. Pearson; and I have witnessed 
the fertilizing effects of a ferruginous water used for 
irrigating a grass meadow made by the Duke of Man- 
chester, at Priestley Bog near Woburn, ^.n account of 
the produce of which has been published by the Board 
of Agriculture. I have no doubt that the peat salt 
and the vitriolic water acted chiefly by producing gyp» 
sum. 

I'he soils on which both are efficacious are cal- 
careous; and sulphate of iron is decomposed by the 
carbonate of lime in such soils. The sulphate of iron 
consists of sulphuric acid and oxide of iron, and is an 
acid and a very soluble salt; when a solution of it is 
mixed with carbonate of lime, the sulphuric acid quits 
the oxide of iron to unite to the lime, and the com- 
pounds produced are insipid and comparatively inso- 
luble. 

I collected some of the deposition from the fer- 
ruginous water on the soil in Priestley meadow. I 
found It consisted of gypsum, carbonate of iron, and 
insoluble sulphate of iron. The principal grasses in 
Priestley meadow are, meadow fox-tail, cook's-foot, 
meadow fescue, fiorin, and sweet scented vernal grass. 
i have examined the ashes of three of the grasses. 



[ 299 ] 

meadow fox-tail, cook's-foot, and fiorin. They con- 
tained a considerable proportion of gypsum. 

Vitriolic impregnations in soils where there is no 
calcareous matter, as in a soil from Lincolnshire, to 
which I referred in the Fourth Lecture, are injurious; 
but it is probably in consequence of their supplying an 
excess of ferruginous matter to the sap. Oxide of 
iron in small quantities forms an useful part of soils; 
and, as is evident from the details in the Third Lec- 
ture, it is found in the ashes of plants; and probably, 
is hurtful only in its acid combinations. 

I have just mentioned certain peats, the ashes of 
which afford gypsum; but it must not be inferred from 
this that all peats agree with them. I have examined 
various peat, ashes from Scotland, Ireland, Wales, and 
the northern and western parts of England, which 
contained no quantity that could be useful; and these 
ashes abounded in siliceous, aluminous earths and 
oxide of iron. 

Lord Charleville found in some peat-ashes from 
Ireland sulphate of potassa; i. e. the sulphuric acid 
combined with potassa. 

Vitriolic matter is usually formed in peats; and if 
the soil or substratum is calcareous, the ultimate re- 
sult is the production of gypsum. In general, when a 
recent peat-ash emits a strong smell resembling that 
of rotten eggs when acted upon by vinegar, it will fur- 
nish gypsum. 

Phosphate of lime is a combination of phosphoric 
acid and lime, one proportion of each. It is a com- 
pound insoluble in pure water, but soluble in water 



C 300 ] 

containing any acid matter. It forms the greatesjt 
part of calcined bones. It exists in most excremen- 
titious substances, and is found both in the straw and 
grain of wheat, barley, oats and rye, and likewise in 
beans, peas, and tares. It exists in some places in 
these islands native; but only in very small quantities. 
Phosphate of lime is generally conveyed to the land in 
the composition of other manure; and it is probably 
necessary to corn crops and other white crops. 

Bone ashes ground to powder will probably be 
found useful on arable lands containing much vegeta- 
ble matter; and may perhaps enable soft peats to pro- 
duce wheat; but the powdered bone in an uncalchied 
state is much to be preferred in all cases when it can 
be procured. 

The Salins compounds of magnesia will require 
very little discussion as to their uses as manures. — 
The most important relations of this subject to agri- 
culture have been considered in the former part of 
this Lecture, when the application of the magnesian 
limestone was examined. In combination with sul- 
phuric acid magnesia forms a soluble salt. This sub- 
stance, it is stated by some enquirers, has beeen found 
of use as a manure; but it is not found in nature in suf- 
ficient abundance, nor is it capable of being made ar- 
tificially sufficiently cheap to be of useful apphcation in 
the common course of husbandry. 

Wood ashes consist principally of the vegetable 
alkali united to carbonic acid; and as this alkali is 
found in almost all plants, it is not difficult to con- 
ceive that it may form an essential part of their or- 



C ^«i ] 

gans. The general tendency of the alkalies is to give 
solubility to vegetable matters ; and in this way they 
may render carbonaceous and other substances capa- 
ble of being taken up by the tubes in the radicle 
iibres of plants. The vegetable alkali likewise has a 
strong attraction for water, and even in small quanti- 
ties may tend to give a due degree of moisture to the 
soil, or to other manures j though this operation from 
the small quantities used, or existing in the soil, can 
be only of a secondary kind. 

The mineral alkali or soda, is found in the ashes 
of sea-weed, and may be procured by certain chemical 
agencies from common j^r--' C^pjcHnqn salt, consists of 
the metal named ser^ium, cbmbihed w ith chlorine ; 
and pure soda consists of the same metal united to 
oxygene. When water is present which can afford 
oxygene to the sodium, soda may be obtained m se- 
veral modes from salt. 

The same reasoning will apply to the operation 
of the pure mineral alkali, or the carbonated alkali, as 
to that of the vegetable alkali ; and when common salt 
acts as a manure, it is probably by entering into the 
composition of the plant in the same manner as gyp- 
sum, phosphate of lime, and the alkalies. Sir John 
Pringle has stated, that salt in small quantities assists 
the decomposition of animal and vegetable matter. 
This circumstance may render it useful in certain 
soils. Common salt likewise is offensive to insects. — 
That in small quantities it is sometimes a useful man- 
ure, I believe it fully proved ; and it is probable that 
its efficacy depends upon many combined causes. 



IJ 302 3 j 

Some persons have argued against the employ- 
ment of salt ; because when used in large quantities, 
it either does no good, or renders the ground sterile j, > 
but this is a very unfair mode of reasoning. That sale *' 
in large quantities rendered land barren, was known 
long before any records of agricultural science exist- 
ed. We read in the Scriptures, that Abimelech tool^,j 
the city of Shechem, " and beat down the city, and" ' 
sowed it with salt ;'* that the soil might be for ever un- 
fruitful. Virgil reprobates a salt soil ; and Pliny, 
though he recommends giving salt to cattle, yet af- 
firms, that when strewed over land it renders it bar- i 
ren. But these are not arguments against a proper 
application of it. Refuse salt in Cornwall, which, how- 
ever, likewise contains some of the oil and exuviae of ; 
fish, has long been known as an admirable manure. 
And the Cheshire farmers contend for the benefit of 
the peculiar produce of their country. 

It is not unlikely that the same causes influence 
the effects of salt, as those which act in modifying the 
operation of gvpsum. Most laPxds in this Island, par- 
ticularly those near the sea, probably contain a sufli- 
cient quantity of salt for all the purposes of vegetation ; 
and in such cases the supply of it to the soil will not 
only be useless, but may be injurious. In great 
storms the spray of the sea has been carried more 
than 50 miles from the shore ; so that from this 
source salt must be often supplied to the soil. I have 
found salt in all the sandstone rocks that I have ex- 
amined, and it must exist in the soil derived from 
these rocks. It is a constituent likewise of almost 
every kind of animal and vegetable manure. 



[ 303 ] 

Besides these compounds of the alkaline earths 
and alkalies, many others have been recommended 
for the purposes of increasing vegetation ; such are 
nitrCy or the nitrous acid combined with potassa. Sir 
Kenelm Digby states, that he made barley grow very 
luxuriantly by watering it with a very weak solution 
of nitre ; but he is too speculative a writer to awaken 
confidence in his results. This substance consists of 
one proportion of azote, six of oxygene, and one of 
potassium ; and it is not unlikely that it may furnish 
azote to form albumen or gluten in those plants that 
contain them ; but the nitrous salts are too valuable 
for other purposes to be used as manures. 

Dr. Home states, that sulphate of potassa, which 
as I just now mentioned, is found in the ashes of some 
peats, is a useful manure. But Mr. Naismith* ques- 
tions his results ; and quotes experiments hostile 
to his opinion, and, as he conceives, unfavourable to 
the efficacy of any species of saline manure. 

Much of the discordance of the evidence relating 
to the efficacy of saline substances depends upon the 
circumstance of their having been used in different 
proportions, and in general in quantities much too 
large. 

I made a number of experiments in May and 
June, 1807, on the effects of different saline substan- 
stances on barley and on grass growing in the same 
garden, the soil of which was a light sand, of which 
100 parts were composed of 60 parts of silice- 
% , ^_ , 

• Elements nf Agriculture, p. 7«, 



'J^ 



C S04 ] 

ous sand, and 24 parts finely divided matter, consist- 
ing of 7 parts carbonate of lime, 12 parts aluminsi 
and silica, less than one part saline matter, principally 
common salt, with a trace of gypsum and sulphate of 
magnesia : the remaining 1 6 parts were vegetable 
matter. 

The solutions of the saline substances were used 
twice a week, in the quantity of two ounces, on spot[ 
of grass and corn, sufficiently remote from each other 
to prevent any interference of results. The substan 
ces tried were super-carbonate, sulphate^ acetate, ni- 
trate, and muriate of potassa ; sulphate of soda, sul- 
phate, nitrate, muriate, and carbonate of ammonia. I 
found that in all cases when the quantity of the salt 
equalled 3^0 P^i't of the weight of the water, the effects 
were injurious ; but least so in the instances of the 
carbonate, sulphate, and muriate of ammonia. When 
the quantities of the salts were iW part of the solution 
the effects were different. The plants watered with 
the solutions of the sulphates grew just in the same 
manner as similar plants watered with rain water. 
Those acted on by the solution of nitre, acetate, and 
super-carbonate of potassa, and muriate of ammonia 
grew rather better. Those treated with the solution 
of carbonate of ammonia grew most luxuriantly of all. 
This last result is what might be expected, for car- 
bonate of ammonia consists of carbon, hydrogene, 
azote, and oxygene. There was, however, another 
result which I had not anticipated ; the plants water- 
ed with solution of nitrate of ammonia di^ not grow 
better than those watered with rain water. The solu- 



[ 30^ ] 

tion reddened litmus paper; and probably the free acid 
exerted a prejudicial effect, and interfered with the re- 
sult. 

Soot doubtless owes a part of its efficacy to the 
ammoniacal salts it contains The liquor produced by 
the distillation of coal contains carbonate and acetate 
of ammonia, and is said to be a very good manure. 

In 1 808, 1 found the growth of wheat in a field at 
Roehampton assisted by a very weak solution of ace- 
tate of ammonia. 

Soapers' waste has been recommended as a man* 
ure, and it has been supposed that its efficacy depend- 
ed upon the different saline matters it contains; but 
their quantity is very minute indeed, and its principal 
ingredients are mild lime and quicklime. In the soap- 
ers* waste from the best manufactories, there is scarce^ 
ly a trace of alkali. Lime moistened with sea water 
affords more of this substance, and is said to have 
been used in some cases with more benefit than conl- 
mon lime. 

It is unnecessay to discuss to any greater extent 
the effects of saline substances on vegetation; except 
the ammoniacal compounds, or the compounds con^ 
taining nitric, acetic, and carbonic acid; none of them 
can afford by their decomposition any of the common 
principles of vegetation, carbon, hydrogene, and oxy- 
gene. 

The alkaline sulphates and the earthy muriates 
are so seldom found in plants, or are found in such 
minute quantities, that it can never be an object 
to apply them to the soil. It was stated in the begin- 

1^ 2 



[ 306 ] 

ning of this Lecture, that the earthy and alkaline sub« 
stances seem never to be formed in vegetation^ and 
there is every reason likewise to believe, that they are 
never decomposed; for after being absorbed they are 
found in their ashes. 

The metallic bases of them cannot exist in con- 
tact with aqueous fluids; and these metallic bases, 
like other metals, have not as yet been resolved into 
any other forms of matter by artificial processes; they 
combine readily with other elements; but they remain 
undestructible, and can be traced undiminished in 
quantity, through their diversified combinations. 



307 ] 



LECTURE VIII. 

On the Improvement of Lands ^y Burning; chemical 
Principles of this Operation. On Irrigation and its 
effects. On Fallowing; its Disadvantages and 
Uses, On the convertible Husbandry founded on 
regtdar Rotations of different Crops. On Pasture: 
Views connected with its Application. On various 
Agricultural Objects connected with Chemistry. 
Conclusion, 

The improvement of sterile lands by burning 
was known to the Romans. It is mentioned by Vir- 
gil in the first book of the Georgics: ** Saepe etiam 
steriles incendere profuit agros.'* It is a practice still 
much in use in many parts of these Islands; the theory 
of its operation has occasioned much discussion; both 
amongst scientific men and farmers. It rests entirely 
upon chemical doctrines; and I trust I shall be able to 
offer you satisfactory elucidations on the subject. 

The basis of all common soils, as I stated in the 
Pourth Lecture, are mixtures of the primitive earths 
and oxide of iron; and these earths have a certain de- 
gree of attraction for each other. To regard this at- 
traction in its proper point of view, it is only necessary 
to consider the composition of any common siliceous 



[ 308 3 

stone. Feldspar, for instance, contains siliceous, al- 
uminous, calcareous earths, fixed alkali, and oxide of 
iron, which exist in one compound, in consequence of 
their chemical attractions for each other. Let this- 
stone be ground into impalpable powder, it then be- 
comes a substance like clay: if the powder be heated 
very strongly it fuses, and on cooling forms a coher- 
ent mass similar to the original stone; the parts separ- 
ated by mechanical division adhere again in conse- 
quence of chemical attraction. If the powder is heat- 
ed less strongly the particles only superficially com- 
bine with each other, and form a gritty mass, which, 
when broken in to pieces, has the characters of sand. 

If the power of the powdered feldspar to absorb 
water from the atmosphere before, and after the ap- 
plication of the heat, be compared, it is found much 
less in the last case. 

The same effect takes place when the powder of 
other siliceous or aluminous stones is made the sub- 
ject of experiment. 

I found that two equal portions of basalt ground 
into impalpable powder, of which one had been strong- 
ly ignited, and the other exposed only to a temperature 
equal to that of boiling water, gained very different 
weights in the same time when exposed to air. In 
four hours the one had gained only two grains, whilst 
the other had gained seven grains. 

When clay or tenacious soils are burnt, the effect 
is of the same kindj they are brought nearer to a stat^ 
analogous to that of sands. 



C S09 ] 

In the manufacture of bricks the general principle 
is well illustrated ; if a piece of dry brick earth be ap- 
plied to the tongue it will adhere to it very strongly, 
in consequence of its power to absorb water ; but af- 
ter it has been burnt there will be scarcely a sensible 
adhesion. 

The process of burning renders the soil less com- 
pact, less tenacious and retentive of moisture ; and 
when properly applied, may convert a matter that was 
stiff, damp, and in consequence cold, into one pow- 
dery, dry, and warm j and much more proper as a 
bed for vegetable life. 

The great objection made by speculative chemists 
to paring and burning, is, that it destroys vegetable 
and animal matter, or the manure in the soil ; but in 
cases in which the texture of its earthy ingredients is 
permanently improved, there is more than a compen- 
sation for this temporary disadvantage. And in some 
soils where there is an excess of inert vegetable mat- 
ter, the destruction of it must be beneficial ; and the 
carbonaceous matter remaining in the ashes may be 
more useful to the crop than the vegetable fibre, from 
which it was produced. 

I have examined by a chemical analysis three 
specimens of ashes from diiferent lands that had un- 
dergone paring and burning. The first was a quanti- 
ty sent to the Board by Mr. Boys of Bellhanger, in 
Kent, whose treatise on paring and burning has been 
published. They were from a chalk soil, and 200 
grains contained 

80 Carbonate of lime. 
11 Gypsum. 



[ 810 ] 

9 Charcoal. 
1 5 Oxide of iron. 
3 Saline matter. 
Sulphate of potash. 
Muriate of magnesia, with a minute 
quantity of vegetable alkali. 
The remainder alumina and silica. 

Mr. Boys estimates that 2660 bushels are the 
common produce of an acre of ground, which, accor- 
ding to his calculation would give 1 72900 lbs. con- 
taining 

Carbonate of lime 69 1 60 lbs. 
Gypsum - 9509.5 

Oxide of iron 12967.5 

Saline matter 2593.5 

Charcoal 7780.5 

In this instance there was undoubtedly a very 
considerable quantity of matter capable of being ac- 
tive as manure produced in the operation of burning. 
The charcoal was very finely divided ; and exposed 
on a large surface on the field, must have been gradu- 
ally converted into carbonic acid. And gypsum and 
oxide of iron, as I mentioned in the last Lecture, seem 
to produce the very best effects when applied to lands 
containing an excess of carbonate of lime. 

The second specimen was from a soil near Cole- 
orton, in Leicestershire, containing only four per cent, 
of carbonate of lime, and consisting of three-fourths 
light siliceous sand, and about one-fourth clay. This 
had been turf before burning, and 100 parts of the 
ashes gave 



C 311 3 

6 parts charcoal. \ 

3 Muriate of soda and sulphate of potash, 

■with a trace of vegetable alkali. 
9 Oxide of iron. 
And the remainder the earths. 

In this instance, as in the other, finely divided 
charcoal was found ; the solubility of which would be 
increased by the presence of the alkali. 

The third instance was, that of a stiff clay, from 
Mount's Bay Cornwall. This land had been brought 
into cultivation from a heath by burning about ten 
years before ; but having been neglected, furze was 
springing up in different parts of it, which gave rise 
to the second paring and burning. 100 parts of the 
ashes contained 

8 parts of charcoal. 

2 of saline matter, principally common salt, 
with a little' vegetable alkali. 

7 Oxide of iron. 

2 Carbonate of lime. 
Remainder alumina and silica. 

Here the quantity of charcoal was greater than in 
the other instances. The salt, I suspect, was owing 
to the vicinity of the sea, it being but two miles off. 
In this land there was certainly an excess of dead ve- 
getable fibre, as well as unprofitable living vegetable 
matter ; and I have since heard, that a great improve- 
ment took place. 

Many obscure causes have been referred to for 
the purpose of explaining the effects of paring and 
burning j arid I believe they may be referred entirely 



C 312 j 

to the diminution of the coherence and tenacity of 
clays, and to the destruction of inert, and useless ve- 
getable matter, and its conversion into a manure. 

Dr. Darwin, in his Phytologia, has supposed, 
that clay during torrefaction, may absorb some nutri- 
tive principles from the atmosphere that afterwards 
may be supplied to plants ; but the earths are pure 
metallic oxides, saturated with oxygene ; and the ten- 
dency of burning is to expel any other volatile princi- 
ples that they may contain in combination. If the 
oxide of iron in soils is not saturated with oxygene, 
torrefaction tends to produce its further union with 
this principle ; and hence in burning, the colour of 
clays changes to red. The oxide of iron containing 
its full proportion of oxygene has less attraction for 
acids than the other oxide, and is consequently less 
likely to be dissolved by any fluid acids in the soil ; 
and it appears in this state to act in the same manner 
as the earths, A very ingenious author, whom I 
quoted at the end of the last Lecture, supposes that the 
oxide of iron when combined with carbonic acid is 
poisonous to plants ; and that one use of torrefaction 
is to expel the carbonic acid from it j but the carbon- 
ate of iron is not soluble in water, and is a very inert 
substance ; and I have raised a luxuriant crop of cres- 
ses in a soil composed of one-fifth carbonate of iron, 
and four-fifths carbonate of lime. Carbonate of iron 
abounds in some of the most fertile soils in England^ 
pai'ticularly the red hop soil. And there is no theo- 
retical ground for supposing, that carbonic acid, which 
is an essential food of plants, should in any of its com- 



[ 313 J 

binations be poisonous to them; and it is known tliat. 
lime and magnesia are both ndxious to vegetation, 
unless combined with this principle. 

Ail soils that contain too much dead vegetable 
fibre, and which consequently lose from one-third to 
one-half of their weight by incineration, and all such 
as contain their earthy constituents in an impalpable 
state of division, i. e. the stiff clays and marks, are im- 
proved by burning; but in coarse sands, or rich' soils 
containing a just mixture of the earths; and in all ca* 
ses in which the texture is already sufficiently loose, 
or the organizable matter sufficiently soluble, the pro- 
cess of torrefaction cannot be useful. 

All poor siliceous sands must be injured by it; 
and here practice is found to accord with the theory, 
Mr. Young, in his Essay on Manures, states, " that 
he found burning injure sand;" and the operation is 
never performed by good agriculturists upon siliceous 
sandy soils, after they have once been brought into 
cultivation. 

An intelligent farmer in Mount's Bay told me, 
that he had pared and burned a small field several 
years ago, which he had not been able to bring again 
into good condition. I examined the spot, the grass was 
very poor and scanty, and the soil an arid siliceous 
sand. 

Irrigation or Watering land^ is a practice, which 
at first view, appears the reverse of torrefaction; and 
in general, in nature, the operation of water is to bring 
earthy substances into an extreme state of division s 
But in the artificial watering of meadows, the benefi- 

$2 



[ 314 3 

cial efiects depend upon many different causes, some 
chemical, some mechanical. 

Water is absolutely essential to vegetation; and 
when land has been covered by water in the winter, 
or in the beginning of spring, the moisture that has 
penetrated deep into the soil, and even the subsoil, 
becomes a source of nourishment to the roots of the 
plant in die summer, and prevents those bad effects 
that often happen in lands in their natural state, from 
a long continuance of dry weather. 

When the water used in irrigation has flowed 
over a calcareous country, it is generally found im- 
pregnated with carbonate of lime; and in this state it 
tends, in many instances, to ameliorate the soil. 

Common river water also generally contains a 
certain portion of organizable matter, which is much 
greater afier rains, than at other times; and which ex- 
ists in the largest quantity when the stream rises in a 
cultivated country. 

Even in cases when the water used for flooding 
is pure, and free from animal or vegetable substances, 
it acts by causing the more equable diffusion of nutri- 
iTve matter existmg m the land; and in very cold sea- 
sons it preserves the tender roots and leaves of the 
grass from being affected by frost. 

Water is of greater specific gravity at 42° Fah- 
renheit, than at 32°, the freezing point; and hence in 
a meadow irrigated in winter, the water immediately 
in contact with the grass is rarely below 40°, a degree 
of temperature not at all prejudicial to the living or- 
gans of plants. 



[SIS 3 

In 1804, in the month of March, I examined 
the temperature in a water meadow near Hungerford, 
in Berkshire, by a very delicate thermometer. The 
temperature of the air at seven in the morning was 
29°. The water was frozen above the grass. The 
temperature of the soil below the water in which the 
roots of the grass were fixed, was 43°. 

In general those waters which breed the best fish 
are the best fitted for watering meadows; but most of 
the benefits of irrigation may be derived from any kind 
of water. It is, however, a general principle, that wa- 
ters containing ferruginous impregnations, though 
possessed of fertilizing effects, when applied to a cal- 
careous soil, are injurious on soils that do not effer- 
vesce with acidsj and that calcareous waters which are 
known by the earthy deposit they afford when boiled, 
are of most use on siliceous soils, or other soils con- 
taining no remarkable quantity of carbonate of lime. 

The most important processes for improving 
land, are those which have been already discussed, 
and that are founded upon the circumstance of remo- 
ving certain constituents from the soil, or adding 
others or changing their nature; but there is an opera- 
tion of very ancient practice still much employed, in 
which the soil is exposed to the air and submitted to 
processes which are purely mechanical, namely, 
fallowing. 

The benefits arising from fallows have been much 
over-rated. A summer fallow, or a clean fallow, 
may be sometimes necessary in lands overgrown with 
weeds, particularly if they are sands which cannot be 



C 316 ] 

pared and burnt with advantage; but it is certainly un- 
profitable as part of a general system in husbandry. 

It has been supposed by some writers, that cer- 
tain principles necessary to fertility are derived from 
the atmosphere, which are exhausted by a succession 
of crops, and that these are again supplied during the 
repose of the land, and the exposure of the pulverised 
soil to the influence of the air; but this in truth is not 
the case. The earths commonly found in soils can- 
not be combined with more oxygene; none of them 
unite to azote; and such of them as are capable of at- 
tracting carbonic acid, are always saturated with it in 
those soils on which the practice of fallowing is adopt- 
ed. The vague ancient opinion of the use of nitre, 
and of nitrous salts in vegetation, seems to have been 
one of the principal speculative reasons for the de- 
fence of summer fallows. Nitrous salts are produced 
during the exposure of soils containing vegetable and 
animal remains, and in greatest abundance in hot wea- 
ther; but it is probably by the combination of azote 
from these remains with oxygene in the atmosphere 
that the acid is formed; and at the expence of an ele- 
ment, which otherwise would have formed ammonia; 
the compounds of which, as is evident from what was 
stated in the last Lecture, are much more efficacious 
than the nitrous compounds in assisting vegetation. 

When weeds are buried in the soil, by their gra- 
dual decomposition they furnish a certain quantity of 
soluble matter; but it may be doubted whether there 
is as much useful manure in the land at the end of a 
clean fallow, as at the time the vegetables clothing the 



C 317 ] 

jsurface were first ploughed in. Carbonic acid gas 
Ss formed during the whole time by the action of the 
rv'egetable matter upon the oxygene of the air, and the 
[greater part of it is lost to the soil in which it was 
formed , and dissipated in the atmosphere. 

The action of the sun upon the surface of the 
soil tends to disengage the gaseous and the volatile 
I fluid matters that it contains ; and heat increases the 
rapidity of fermentation : and in the summer fallow, 
nourishment is rapidly produced, at a time when no 
vegetables are present capable of absorbing it. 
- Land when it is not employed in preparing food 
for animals, should be applied to the purpose of the 
preparation of manure for plants ; and this is effected 
by means of green crops, in consequence of the ab- 
sorption of carbonaceous matter in the carbonic acid 
of the atmosphere. In a summer's fallow a period is 
always lost in which vegetables may be raised, either 
as food for animals, or as nourishment for the next 
crop ; and th^ texture of the soil is not so much im- 
proved by its exposure as in winter, when the expan- 
sive powers of ice, the gradual dissolution of snows, 
and the alternations from wet to dry, tend to pulverize 
it, and to mix its different parts together. 

In the drill husbandry the land is preserved 
clean by the extirpation of the weeds by harid, and by 
raising the crops in rows, which renders the destruc- 
tion of the weeds much more easy. Manure is sup- 
plied either by the green crops themselves, or from 
the dung of the cattle fed upon them ; and the plants 
having large systems of leaves, are made to alternate 
with those bearing grain. 



I 318 3 J] 

It is a great advantage in the convertible system 
t>f cultivation, that the whole of the manure is em- 
ployed ; and that those parts of it which are not fitted 
for one crop, remain as nourishment for another* 
Thus, in Mr. Coke*s course of crops, the turnip is the 
first in the order of succession ; and this crop is man- 
ured with recent dung, which immediately affords suf- 
ficient soluble matter for its nourishment ; and the heat 
produced in fermentation assists the germination of 
the seed and the growth of the plant. After turnips, 
barley with grass seeds is sown ; and the land having 
been little exhausted by the tu-rnip crop, affords the 
soluble parts of the decomposing manure to the grain. 
The grasses, rye grass, and clover remain, which de- 
rive a small part only of their organised matter from 
the soil, and probably consume the gypsum in the 
manure which would be useless to other crops : these 
plants likewise by their large systems of leaves, absorb 
a considerable quantity of nourishment from the atmos- 
phere ; and when ploughed in at the end of two years, 
the decay of their roots and leaves affords manure for 
the wheat crop ; and at this period of the course, the 
woody fibre of the farm-yard manure which contains 
the phosphate of lime and the other difficultly soluble 
parts, is broken down : and as soon as the most ex- 
hausting crop is taken, recent manure is again ap- 
plied. 

Mr. Gregg, whose very enlightened system of 
cultivation has been published by the Board of Agri- 
culture, and who has the merit of first adopting a plan 
similar to Mr. Coke's upon strong clays, suffers the 



iground after barley to remain at rest for two years ia 
Igrass ; sows peas and beans on the lays ; ploughs in 
tithe pea or bean stubble for wheat ; and in some in- 
stances, follows his wheat crops by a course of winter 
tares and winter barley, which is eat off in the spring, 
I before the land is sowed for turnips. 

Peas and beans, in all instances, seem well adapt- 
ed to prepare the ground for wheat ; and in some 
rich lands, as in the alluvial soil of the Parret, men- 
tioned in the Fourth Lecture, and at the foot of the 
South Downs in Sussex, they are raised in alternate 
crops for years together. Peas and beans contain, as 
appears from the analyses in the Third Lecture, a 
small quantity of a matter analogous to albumen ; but 
it seems that the azote which forms a constituent part 
of this matter, is derived from the atmosphere. The 
dry bean leaf, when burnt, yields a smell approaching 
to that of decomposing animal matter ; and in its de- 
cay in the soil, may furnish principles capable of be- 
coming a part of the gluten in wheat. 

Though the general composition of plants is very 
analogous, yet the specific difference in the products 
of many of them, and the facts stated in the last Lec- 
ture, prove that they must derive different materials 
from the soil 5 and though the vegetables having the 
smallest systems of leaves will proportionably most 
exhaust the soil of common nutritive matter, yet par- 
ticular vegetables when their produce is carried off, 
will require peculiar principles to be supplied to the 
land in which they grow. Strawberries and potatoes 
at first produce luxuriantly in virgin mould recently 



[ 320 J 

turned up from pasture ; but in a few years they dt:- 
generate, and require a fresh soil ; and the or;i:aniza- 
tion of these plants is such, as to be constantly pro- 
ducing the migration of their layers : thus the straw- 
berry by its long shoots is constantly endeavouring to 
occupy a new soil ; and the fibrous radicles of thi 
potatoe produce bulbs at a considerable distance from 
the parent plant. Lands in a course of years often 
cease to afford good cultivated grasses ; they become 
(as it is popularly sai.i) tired of them ; and one of the 
probable reasons for this was stated in the last Lec- 
ture. 

The most remarkable instances of the powers of 
vegetables to exhaust the soil of certain principles ne- 
cessary to their growth is found in certain funguses. 
Mushrooms are said never to rise in two successive 
seasons on the same spot ; and the production of the 
phsenomena called fairy rings has been ascribed by 
Dr WoHaston to the power of the peculiar fungus 
which forms it to exhaust the soil of the nutriment 
necessary for the growth of the species. The conse- 
quence is, that the ring annually extends ; for no 
seeds will grow where their parents grew before them ; 
and the interior part of the circle has been exhausted 
by preceding crops ; but where the fungus has died, 
nourishment is supplied for grass, which usuaHy rises 
within the circle, coarse, and of a dark green colour. 

When cattle are fed upon land not benefitted by 
their manure, the effect is always an exhaustion of the 
soil ; this is particularly the case where carrying 
horses are kept on estates ; they consume the pasture 



[ 321 3 

during the night, and drop the greatest part of their 
manure during their labour in the day-time. 

The exportation of grain from a country, unless 
some articles capable of becoming manure are intro- 
duced in compensation, must ultimately tend to ex- 
haust the soil. Some of the spots now desart sands in 
northern Africa, and Asia Minor, were anciently fer- 
tile. Sicily was the granary of Italy : and the quan- 
tity of corn carried off from it by the Romans, is pro- 
bably a chief cause of its present sterility. In this Is^ 
land, our commercial system at present has the effect 
of affording substances which in their use and decom- 
position must enrich the land. Corn, sugar, tallow, 
oil, skins, furs, wine, silk, cotton, &c. are imported, 
and fish are supplied from the sea. Amongst our 
numerous exports woollen, and linen, and leather 
goods, are almost the only substances which contain 
any nutritive materials derived from the soil. 

In all courses of crops it is necessary that every 
part of the soil should be made as useful as possible 
to the different plants ; but the depth of the furrow 
in ploughing must depend upon the nature of the soil, 
and of the subsoil. In rich clayey soils the furrow 
can scarcely be too deep ; and in sands, unless the 
subsoil contains some principles noxious to vegetables, 
the same practice should be adopted. When the roots 
are deep they are less liable to be injured, either by 
excess of rain, or drought ; the layers shoot forth 
their radicles into every part of the soil ; and the 
space from which the nourishment is derived is more 

T 2 



t 322 3 

Considerable, than when the seed is superficially inser- 
ted in the soil. 

There has been much difference of opinion with 
respect to permanent pasture ; but the advantages or 
disadvantages can only be reasoned upon according to 
the circumstances of situation and climate. Under 
the circumstances of irrigation, lands are extremely 
productive with comparatively little labour ; and in 
climates where great quantities of rain falls, the natur- 
al irrigation produces the same effects as artificial. 
When hay is in great demand, as sometimes happens 
in the neighbourhood of the metropolis, where man- 
ure can be easily procured, the application of it to pas- 
ture is repaid for by the increase of crop ; but top- 
dressing grass land with animal or vegetable manure, 
cannot be recommended as a general system. Dr. 
Coventry very justly observes, that there is a greater 
waste of the manure in this case, than when it is 
ploughed into the soil for seed crops. The loss by 
exposure to the air, and the sunshine, offer reasons in 
addition to those that have been already quoted in the 
Sixth Lecture, for the application of manure even in 
this case, in a state of incipient, and not completed 
fermentation. 

Very little attention has been paid to the nature 
of the grasses best adapted for permanent pasture. 
The chief circumstance which gives value to a grass, 
is the quantity of nutritive matter that the whole crop 
will afford ; but the time and duration of its produce 
are likewise points of great importance ; and a grass 
that supplies green nutriment throughout the whole of 



C S23 ] 

the year, may be more valuable than a grass which, 
yields its produce only in summer, though the whole 
quantity of food supphed by it should be much less. 

The grasses that propagate themselves by layers, 
the different species of Agrostis, supply pasture 
throughout the year ; and, as it has been mentioned 
on a former occasion, the concrete sap stored up in 
their joints, renders them a good food even in winter. 
I saw four square yards of fiorin grass cut in the end 
of January, this year, in a meadow exclusively appro- 
priated to cultivation of fiorin, by the Countess of 
Hardwicke, the soil of which is a damp stiff clay. 
They afforded 28 pounds of fodder ; of which 1000 
parts afforded, 64 parts of nutritive matter, consisting 
nearly of one-sixth of sugar, and five-sixths of mucil- 
age, with a little extractive matter, In another expe- 
riment, four square yards gave 27 pounds of grass. 
The quality of this grass is inferior to that of the fio- 
rin referred to in the Table, in the latter part of the 
Third Lecture, which was cultivated by Sir Joseph 
Banks in Middlesex, in a much richer soil, and cut i.n 
December, 

The fiorin grass, to be in perfection, requires a 
moist climate or a wet soil ; and it grows luxuriantly 
in cold clays unfitted for other grasses. In light sands 
and in dry situations its produce is much inferior as 
to quantity and quality. 

The common grasses, properly so called, that 
afford most nutritive matter in early spring, are the 
vernal meadow grass, and meadow foxtail grass ; but 
their produce at the time of flowering and ripening 



[ 324 3 

the seed, are inferior to that of a great number of 
other grasses ; their latter math is, however, abun- 
dant 

Tall fescue grass stands highest, according to 
the experiments of the Duke of Bedford, of any grass, 
properly so called, as to the quantity of nutritive mat- 
ter afforded by the whole crop when cut at the time of 
flowering ; and meadow cat's-tail grass affords most 
food when cut at the time the seed is ripe ; the high- 
est latter math produce of the grasses examined in the 
Duke of Bedford's experiments is from the sea mea- 
dow grass. 

Nature has provided in all permanent pastures a 
mixture of various grasses, the produce of which dif- 
fers at different seasons. Where pastures are to be 
made artificially such a mixture ought to be imitated ; 
and, perhaps, pastures superior to' the natural ones 
may be made by selecting due proportions of those 
species of grasses fitted for the soil, which afford res- 
pectively the greatest quantities of spring, summer, 
latter math, and winter produce ; a reference to the 
details in the Appendix will shew, that such a plan of 
cultivation is very practicable. 

In all lands, whether arable or pasture, weeds of 
ever description should be rooted out before the seed 
is ripe ; and if they are suffered to remain in hedge 
rows, they should be cut when in flower, or before, 
and made into heaps for manure j in this case they 
will furnish more nutritive matter in their decomposi- 
tion ; and their increase by the dispersion of seeds will 
Ije prevented. The farmer, who suffers weeds to re- 



t 325 3 

main till their ripe seeds are shed, and scattered by 
the winds, is not only hostile to his own interests, but 
is likewise an enemy to the public: a few thistles will 
stock a whole farm; and by the light down which is 
attached to their seeds, they may be destributed over 
a whole country. Nature has provided such ample 
resources for the continuance of even the meanest ve- 
getable tribes, that it is very difficult to ensure the de- 
struction of such as are hostile to the agriculturist, 
even with every precaution. Seeds excluded from 
the air, will remain for years inactive in the soil,* and 
yet germinate under favourable circumstances; and the 
different plants, the seeds of which, like those of the 
thistle and dandelion, are furnished with beards or 
wings, may be brought from an immence distance. 
The fleabane of Canada has only lately been found in 
Europe; and Linnaeus supposes that it has been trans- 
ported from America, by the very light downy plumes 
with which the seed is provided. 

In feeding cattle with green food there are many 
advantages in soilings or supplying them with food, 
where their manure is preserved, out of the field; the 



• The appearance of seeds in places where their parent plants are not found 
may be easily accounted for from this circumstance, and other circumstances. Many 
seeds are carried from island to island by currents in the sea, and are defended by 
their hard coats from the immediate action of th» water. West Indian seeds (of 
this description) are often found on our coasts, and readily germinate; their l«ng 
voyage having been barely sufficient to afford the cotyledon its due proportion of 
moisture. Other seeds are carried indigested in the stomach of birds, and suppli- 
ed with food at the moment of their deposition. The light seeds of the mosses 
and lichens, probably float in every part of the atmosphere, and abound on the* 
"^nrfi^e of the sea. 



e 32& 3 

plants are less injured when cut, than when torn or 
jagged with the teeth of the cattle, and no food is 
wasted by being trodden down. They are Hkewise 
obh'ged to feed without making selection; and in con- 
sequence the whole food is consumed: the attachment, 
or dislike to a particular kind of food exhibited by ani- 
mals, offers no proof of its nutritive powers. Caitle 
at first, refuse linseed cake, one of the most nutritive 
substances on which they can be fed.* 



• For the following observations on tlie selection of different kinds of com- 
mon food by sheep and cattle, I am obliged to Mr. George Sinclair. 

" Lolium perenne,Tye srzss. Sheep, eat this giass when it is in the early 
stage of its growth, in preference to most others; but after the seed approaches to- 
wards perfection, they leave it for almost any other kind. A field in the Park of 
"Woburn was laid down in two eqaal parts, one part -with rye grass and white clo- 
ver, and the other part with cock's-foot and red clover: from the spring till mid- 
summer the sheep kept almost constantly on the rye grass; but after that time 
they left it, snd adhered with equal constancy to the cock's-foot during the re« 
maiuder of the season. 

Dacfylis gomerata, coc^t's-(oot. Oxen, horses, and sheep, eat this grass readi- 
ly. The oxen continue to eat the straws and flowers, from the time of flowering, 
'till the time of perfecting the seed; this was exemplified in a striking manner hi 
the field before alluded to. The oxen generally kept to the cock's-foot and red 
clover, and the sheep to the rye-grass and white clover. In the experiments pub- 
lished in the Amccnitates AcademicBe, by the pupils of Linnxus, it is asserted, 
that this grass is rejected by oxen; the above fact, however, is in contridiction 

of it. 

Alopecurw pratemis, meadow fox-tail. Sheep and horses seem to have a 
jrreater relish for this grass than oxen. It delights in a soil of intermediate quality 
as to moisture and dryness, and is very productive. In the water-meadow at 
Priestley, it constitutes a considerable part of the produce of that excellent mea- 
dow. It there keeps invariably possession of the top of the ridges, extending 
generally about six feet from each side of the water course; the space below that 
to where the ridge ends, is stocked with cock's-foot, and the rough stalked mea- 
dow grass, Feituca pratemis, Fatuca dun'usculj, Agrosth stolonifera, AgroHii paU 
vslris, and sweet-scented vernal grass, with a small admixture of some other 
liinds. 

Phhum pratense, meadow cat s-tail. This grass is eaten without reserve, by 
rwen, sheep, and horses. Dr. Pulteney saysj that it is disliked by sheep; but io 



C 327 3 

When food artificially composed is to be given to 
cattle, it should be brought as nearly as possible to the 
state of natural food. Thus, when sugar is given to 



pastures where it abounds, it does not appear to be rejected by these animals; but 
«aten in common with such othe's as are grosvlng with it. Hares are remarkably 
fond of it. The Phleum nodonim, Phleum alpinum, Poafirtilis, and Poa conipresia> 
■^ere left untouched, although they were closely adjoining to it. It seems to at- 
tain the greatest perfection in a rich deep loam. 

Agroitis stotonifera, fiorin. In the experiments detailed in the Amcenitates 
Academics, it is said, that hoi res, sheep, and oxen, eat this grass readily. On the 
Duke of Bedford's farm at Maulden, fiorin hay was placed in the racks before 
horses in small distinct quantities; alternately with common hay; but no decided 
preference for either, was manifested by the horses in this trial. But that cows 
and horses prefer it to hay, when in a green state, seems fully proved by Dr. 
Richardson in his several publications on Fiorin; and of its productive powers in 
England (which has been doubted by some,) there are satisfactory proofs. Lady 
Ilardwicke has given an account of a trial of this grass; wherein 24 milch cows, 
and one young horse, besides a number of pigs, were kept a fortnight on the pro 
^ce of one acre. 

Poa trivialh, rough-stalked meadow. Oxen, horses, and sheep, eat this 
grass with avidity. Hare« also eat it; but they give a decided preference to 
the smoothed-stalked meadow grass, to which it is, in many respects, nearly 
^lied. 

Pea ^r«twj»s, smooth-stalked meadow grass. Oxen and horses, are observed 
to eat this grass in common with others; but sheep rather prefer the hard fescue, 
and sheeps' fescue which affect a similar soil. This species exhausts the soil in a 
greater degree, than almost any other species of grass; the roots being numerous, 
and powerfully creeping, become in two or three years completely matted toge- 
ther; the produce diminishes as this takes place. It grows common in sor&e 
meadows, dry banks, and even on walks. 

Cynosurus cristatus, crested dog's-tail grass. The South Down sheep, anil 
deer, appear to be remarkably fond of this grass: in some parts of Woburn Park 
this grass forms the principal part of the herbage on which these animals chiefly 
browse; while another part of the Park; that contains the J^rostis capillaris, 
.Agrostis pumilis, Festuca ovina, Fettuca duriuscula, and Festuca cambrica, is seldom 
touched by them; but the Welch breed of sheep almost constantly browse upon, 
these, and neglect the Cynoaurus cristatus, Lolium perenne, and Poa trivialis, 

Agrostis vulgarii (capillarii Linn.J, fine bent; common bent. This is a vet'y 
common grass on all poor dry sandy soils. It is not palatable to cattle, as they 
never eat it readily, if any other kinds be within their reach. The Welch sheep, 
however, prefer it, as I before observed; and it is singular, that those sheep 
being bred in thft park, when some ol' the best grasses are equally within tlieir 



[ 328 ] 

them, some dry fibrous matter should be mixed with 
J t such as chopped straw, or dry withered grass, in or- 
der that the functions of the stomach and bowels may 



reach, should still prefer those grasses which naturally grow on the Welch moun- 
tains: it seems to argue that such a preference is the effect of some other cause, 
than that of habit. 

Festuca ovina, sheeps' fescue. All kinds of cattle relish this grass; but it ap- 
pears from the trial that has been made with it on clayey soils, that It continues 
but a short time in possession of such, being soon overpowered by the more luxuri- 
ant kinds. On dry shallow soils that are incapable of produeing the larger sorts 
this should form the principal crop, or rather the whole; for it is seldom or ever, in 
its natural state, found intimately mixed with others; but by itself. 

Festuca duriuicuta, h^rd fescue grasss. This is certainly one of the best of the 
dwarf sorts of grasses. It is grateful to all kinds of cattle; horses are very fond of 
it; they cropped it close to the roots, and neglected the Feituca ovina, and Festuca 
rubra, which were contiguous to it. It is present in most good meadows and 
pastures. 

Festuca ^ra/e«,?/.f, meadow fescue. This grass seldom absent from rich mea- 
dows and pastures; it is observed to be highly grateful to oxen, sheep, and horses, 
particularly the former. It appears to grow most luxuriantly when combined 
with Ijie hard fescue, and Pea trivialis. 

Avena eliaior, tall oat grass. This is a very productive grass, frequent in 
meadows and pastures, but is disliked by cattle, particularly by horses; this, per- 
fectly, agrees with the small portion of nutritive which matter it affords. It 
seems to thrive best on a strong tenacious clay. 

Avena fiavescent, yellow oat-gras». This grass seems partial to dry soils, and 
meadows, and appears to be eaten by sheep and oxen, equally with the meadow 
barley, crested dog's-tail, and sweet-scented vernal grasses, which naturally grow 
in company with it. It nearly doubles the quantity of its produce by the appU- 
cation of calcareous manure. 

Holcus lanatus, meadow soft grass. This is a very common grass, and grows 
on all soils, from the richest to the poorest. It affords an abundance of seed, 
which is light, and easily dispersed by the wind. It appears to be generally disli- 
ked by all sorts of cattle. The produce is not so great as a view of it in fields 
would indicate; but being left almost entirely untouched by cattle, it appears as 
the most productive part of the herbage. The hay which h made of it, from the » 
number of downy hairs which cover the surface of the leaves, is soft and spongyJ 
and disliked by cattle in general. 

Anthoxanthum odratum, sweet-scented vernal grass. Horses, oxen, and sheep, 
eat this grass; though in pastures where it is combined with the meadow fox- 
tail, and white clover, cock's-loot, rough-stalked me<idow, it is left untouched, 
from which it would eeem unpalatable to cattle. Mr. Grant, of Leighton, laid 



I 329 J 

be performed in a natural manner. The principle is the 
same as that of the practice alluded to in the Third 
Lecture, of giving chopped straw with barley. 

In washing sheep, the use of water containing 
carbonate of lime should be avoided; for this substance 
decomposes the yolk of the wool, which is an animal 
softp, the natural defence of the wool; and wool often 
washed in calcareous water, becomes rough and more 
brittle. The finest wool, such as that of the Spanish 
and Saxon sheep, is most abundant in yolk. M. Van- 
quelin has analysed several different species of yolk, 
and has found the principal part of all of them a soap, 
with a basis of potassa, (i. e. a compound of oily mat- 
ter and potassa), with a little oily matter in excess. — 
He has found in them likewise, a notable quantity of 
acetate of potassa, and minute quantities of carbonate 
of potassa and muriate of potassa, and a peculiar odor„ 
ous animal matter. 

M. Vanquelin states, that he found some speci- 
mens of wool lose as much as 45 per cent, in being 
deprived of their yolk; and the smallest loss in his 
experiments was 35 per cent. 

The yolk is most useful to the wool on the back 
of the sheep, in cold and wet seasons; probably the 



down one half a field of a considerable extent with this grass, combiqed with 
white clover. The other half of the field with fox-tail and red clover. The sheep 
would not touch the Sweet-scented vernal, but kept constantly upon the fox-tail 
The writer of this, saw the field when the grasses were in the highest state 
of perfection: and hardly any thing could be more satisfactory. Equal quanti- 
ties of the seeds of white clover, were sown with each of the grasses, but from 
the dwarf nature of the sweet-scented venial grass, the clover mixed with it 
had attaintd to greater luxuriance, than that mixed with th« meadow fox-tail. 

u2 



( 330 ) 

application of a little soap of potassa, with excess of 
grease to the sheep brought from warmer climates in 
our winter, that is, increasing their yolk artificially, 
might be useful in cases where the fineness of the 
wool is of great importance. A mixture of this kind 
is more conformable to nature, than that ingeniously 
adopted by Mr. Bakewell; but at the time his labours 
commenced, the chemical nature of the yolk was un- 
known. 



331 



I have now exhausted all the subjects of discus- 
sion, which my experience or information have been 
able to supply on the connection of chemistry with 
agriculture. 

I venture to hope, that some of the views brought 
forward, may contribute to the improvement of the 
most important and useful of the arts. 

I trust that the enquiry will be pursued by- 
others; and that in proportion as chemical philosophy 
advances towards perfection, it will afford new aids to 
agriculture. 

There are sufficient motives connected with both 
pleasure and profit, to encourage ingenius men to pur- 
sure this new path of investigation. Science cannot 
long be despised by any persons as the mere specula- 
tion of theorists; but must soon be considered by all 
ranks of men in its true point of view, as the refine- 
ment of common sense, guided by experience, gradu- 
ally substituting sound and rational principles, for 
vague popular prejudices. 

The soil offers inexhaustible resources, which 
when properly appreciated and employed, must in- 
crease our wealth, our population, and our physical 
strength. 

We possess advantages in the use of machinery, 
and the division of labour, belonging to no other na- 
tion. And the same energy of character, the same ex^ 



V 332 ) 

tent of resources which have always distinguished the 
people of the British Islands, and made them excel in 
arms, commerce, letters, and philosophy, apply with 
the happiest effect to the improvement of the cultiva- 
tion of the earth. Nothing is impossible to labour, 
aided by ingenuity. The true objects of the agricul- 
turist are likewise those of the patriot. Men value 
most what they have gained with effort; a just confi- 
dence in their own powers results from success; they 
love their country better, because they have seen it im- 
proved by their own talents and industry; and they 
identify with their interests, the existence of those in- 
stitutions which have afforded them security, inde- 
pendence, and the multiplied enjoyments of civilized 
life. 



APPENDIX. 



AN 
ACCOUNT OF THE RESULTS 

OF 

EXPERIMENTS ON THE PRODUCE 

AND 

NUTRITIVE QUALITIES 

OF 

DIFFERENT GRASSES, AND OTHER PLANTS, 

USED AS THE FOOD OF ANIMALS. 

mSTlTUTED BY 

JOHN, DUKE OF BEDFORD. 



BOOKS QUOTED IN THE FOLLOWING PAGES. 

Curt. Lond — Flora Londinensis. By William Curtis, 2 vols. 
London 1798, fol. 

Fl. Dan.— Flora Danica, or Icones Plantarum sponte nascen- 
tium in Regnis Daniae et Norvegiae, editae a 
Ge ^der. Hafniae 1761, fol. 

Engl. Bot. — English Bontany, by J. E. Smith, M. D ; the 
Figures by J. Sowerby. London 1790, 8vo. 

W. B.»—Botanical Arrangements. By Dr. Withering. Lon- 
don 1801, 4 vol. 

Huds. — Hudson! Flora Anglica, 1 778, vol. ii. 

Host. G. A. — Nic. Thomae Host Icones et Descriptiones 
Graminum Austriacorum, vol. i. — iii. Vindo- 
bonse, 1801, fol. 

Hqrt. Kew.— Hortus Kewensis. By W, J. Aiton, vol. i. Lon- 
don 1810. 



Introduction by the Editor, 

Of the 215 proper grasses which are capable of 
being cultivated in this climate two only have been 
employed to any extent for making artificial pastures, 
rye grass and cock's foot grass j and their application 
for this purpose seems to have been rather the result 
of accident, than of any proofs of their superiority 
over other grasses. 

A knowledge of the comparative merits and 
value of all the different species and varieties of grasses 
cannot fail to be of the highest importance in practical 
agriculture. The hope of obtaining this knowledge 
was the motive that induced the Duke of Bedford to 
institute this series of experiments. 

Spots of ground, each containing four square 
feet, in the garden at Woburn Abbey, were enclosed 
by boards in such a manner that there was no lateral 
communication between the earth included by the 
boards, and that of the garden. The soil was re- 
moved in these inclosures, and new soils supplied j 
or mixture of soils were made in them, to furnish as 
far as possible to the different grasses those soils which 
seem most favourable to their growth j a few varieties 
being adopted for the purpose of ascertaining the 
effect of different soils on the same plant. 

The grasses were either planted or sown, and 
their produce cut and collected and dried, at the pro- 
per seasons, in summer and autump, by Mr. Sinclair, 



[ IV. ] 

his Grace's gardener. For the purpose of determin- 
ing as far as possible the nutritive powers of the 
different species, equal weights of the dry grasses or 
vegetable substances were acted upon by hot water 
till all their soluble parts, were dissolved ; the solution 
was then evaporated to dryness by a gentle heat in a 
proper stove, and the matter obtained carefully weigh- 
ed. This part of the process was likewise conducted 
with much address and intelligence by Mr. Sinclair, 
by whom all the following details and calculations are 
furnished. 

The dry extracts supposed to contain the nutri- 
tive matter of the grasses, were sent to me for chemi- 
cal examination. The composition of some of them 
is stated in the last table of Chap. III. I shall offer a few 
chemical observations on others at the end of this 
Appendix. It will be found from the general conclu- 
sions, that the mode of determining the nutritive 
power of the grasses, by the quantity of matter they 
contain soluble in water, is sufficiently accurate for all 
the purposes of agricultural investigatioa. 



L V ] 

Details of 'Experiments on Grasses, By George Sin- 
clair, Gardener to his Grace the Duke of Bed- 
ford, and Corresponding Member of the Horticultural 
Society of Edinburgh. 



I. Anthoicatiihuin odoratwn. Engl. Bot. 647. — Curt. 
Lond. 

Sweet-scented vernal grass. Nat. of Britain. 
At the time of flowering, the produce from the space 

of an acre equal to ,00C09 1827364 of a brown 

san4y loam with manure, is 

oz. or lbs. per ac e 

Grass 11 oz. 8 dr.* The produce per acre 125235 — 7827 3 

80 dr. of erass weieh when dry 21 1-2 dr.-) 

n-u 1 f*u aJ An i^inC33656 — 2103 8 

The produce of the space, ditto 49. 1 7-10 3 

The weight lost by the produce of one acre In drying 5723 10 

64 dr. of grass afford of nutritive matter 1 dr. "> 

The produce of the space, ditto 2. 3 5-103 ^^^^ ^^ "" ^^^ ^ ^^ 

At the time the ^eed is ripe the produce is 

Grass, 9 oz. The produce per acre - 98010 — 6125 10 

80 dr. of grass weigh when dry 24 dr. ") 

Tu ^ 1 f.u A- J A<y 11/^^29403 — 1837 11 

The produce of the space, ditto 43. 1-163 

The weight lost by the produce of one acre in drying — 4287 15 

64 dr. of grass afford of nutritive matter 3. 1 dr. " 

The produce of the space ditto 

The weight of nutritive matter which is lost by taking-% 
the crop at the time the grass is in flower, exceed- C 188 12 4 

ing half of its value - - - - • • J 

The proportional value which the grass at the 
time of flowering bears to that at the time the seed is 
ripe, is as 4 to 13. 



• The weight is avoirdupolss ; lbs, pounds, oz. ounces, dr. drachms. The 
weights not named are, quarters of drachms, and fractions of quarters of dracbiBS ; 
thus 7. 1 1.4 means 7 drachms 1 quarter of a drachm and !•< of a quarter. 



r3.ldr.l 

7 1 1-45 ^^^'^ ^° — 311 1 1 



VI. APPENDIX. 

The latter-math produce is oz. or lbs. per acre 

Grass, 10 oz. Tlie ])rodace per acre 108900 ~ 6806 4 

64 dr. of t,'r;iss aft'ord of nutritive matter, 2. 1 dr. 3828 8— 239 4 8 

The proportional vahie which the grass of the 
latter-math bears to that, at the time the seed is ripe, 
is nearly as 9 to 13. 

The smallness of the produce of this grass ren- 
ders it improper for the purpose of hay; but its early 
growth, and the superior quantity of nutritive matter 
which the latter-math affords, compared with the 
quantity afforded by the grass at the time of flowering, 
causes it to rank high as a pasture grass, on such soils 
as are well fitted for its growth; such are peat-bogs, 
and lands that are deep and moist. 

II. Hokus odoratus. Host. G. A. Growing in woods. 

Sweet scented soft grass. Nat. of Germany. Flo. 

Ger. — H Borealis. Growing in moist meadows. 

At the time of flowering, the produce from a rich 

sandy loa/n is 

oz. or lbs. per acre 

Grass, 14 oz. The produce per acre 152460 — 9528 12 

80 dr. of grass weiRh when dry 20. 2 dr. ") 

nx. 1 <..^ v.i r^ 1 <3 r C 39067 14 — 2441 11 14 

1 he produce ot the space, ditto 57 1 2>-S j 

The weight lost by ihe prdduce of one acre in drying 7087 2 

64 dr. of grass afford of nutritive matter 4. 1 dr. t 

The produce of the space, ditto 14 3 1-23 ^^^^'* ^^ "" ^^° ^^ ^ 

At the time the seed is ripe the produce is 

Grass, 40 oz. The produce per acre . 435600 — 27225 

64 dr. of grass weigh when dry 28 dr. 7 

The produce of Uie space, ditto 224 dr.3 ^^^4^^ ^ - ^^^8 12 

'I'lie weight lost by the produce of one acre in drying 17696 4 

64 dr. of gras.s nilbrd of nutritive matter 5. 1 dr. 7 

The produce of the space, ditto 52- 2dr.3 ^^''•^~ ^"^ ~ ^^-^^ ^ '•" 

y\\e weight of nutritive matter which is lost by taking the 
crop at tlie time the gi'ass is \'\ flower, being more than 
half of Its vahif 1600 8 1.0 



APPENDIX. vif. 

The proportional value which the grass at the 
time of flowering bears to that at the time the seed is 
ripe, is as 17 to 21. 

The produce of latter-math is oz. or lbs. per acre 

Grass, 25 oz. The produce per acre 272250 — 17015 10 

64dr.ofgrassaffordofnuU'itivematter4.1 dr. 18079 1 — 1129 15 1 

The grass of the latter-math crop, and of the 
crop at the time of flowering, taking the whole quantity, 
and their relative proportions of nutritive matter, are 
in value nearly as 6 to 10: the value of the grass at 
the time the seed is ripe, exceeds that of the latter-math, 
in proportion as 21 to 17. 

Though this is one of the earliest of the flower- 
ing grasses, it is tender, and the produce in the spring 
is inconsiderable. If, however, the quantity of nutri- 
tive matter which it affords, be compared with that of 
any of those species which flower nearly at the same 
time, it will be found greatly superior. It sends forth 
but a small number of flower stalks, which are of a 
slender structure compared to the size of the leaves. 
This will account in a great measure for the equal 
quantities of nutritive matter afforded by the grass at 
the time of flowering, and the latter-math. 

III. Cynosurus cceruleus* Engl. Bot. 1613. Host. 
G. A. 2. t. 98. Blue moor-grass. Nat. of 
Britain. Sesleria cserulea. 

At the time the seed is ripe the produce from a 
light sandy soil is 

oz. or lbs. per acre 

Grass, 10 oz. The produce per acre 108900 — 6806 4 3 

64 dr. of grass afford of nutritive matter 3 Q dr. 6380 l.S — '?98 12 13 



Mil. APPENDIX. 

The produce of this grass is greater than its ap- 
pearance would denote; the leaves seldom attain to 
more than four or five inches in length, and the flower 
stalks seldom arise to more. Its growth is not rapid 
after being cropped, nor does it seem to withstand 
the effects of frost, which if it happen to be severe 
and early in the spring, checks it so much as to pre- 
vent it from flowering for that season; otherwise the 
quantity of nutritive matter which the grass affords 
(for the straws are very inconsiderable,) would rank 
it as a valuable grass for permanent pasture. 

IV. Alopecurus pratensis. Curt. Lond. AIo. myosur- 
oides. Meadow foxtail-grass. Nat. of Britain. 
Engl. Bot. 848. 
At the time of flowering, the produce from a 

clayey loam is oz. or lbs. per acre 

Grass, 30 oz. The produce per acre 326700 — 20418 12 

80 dr. of grass weijrh when dry 24 dr. '} 

rr. / r.^ A- J. 'i'^t^A C 98010 0— 6125 10 

The produce of the space, ditto 336 dr. 3 

The weig'ht lost by the produce of one acre in drying 14293 2 

64 dr. of grass afford of nutritive matter 1 2 dr. 



The produce of the space, ditto 11 1 dr.^ ''^^^ ^"~ '*^ ^^ ° 

The produce from a sandy loam is 

Grass, 12 oz. 8 dr. The produce per acre 136125 -- 8507 13 

80 dr. of grass weigh when dry 24 dr. ^ 

The produce of the space, ditto 60 dr. 5 ^^^"^"^ 9 — 2552 5 8 

64 dr .of grass afford of nutritive matter 1 dr. 1 

The produce of the space, ditto 3 1-2 > ^^^^ ^^ ~" ^^^ ^* ^^ 

At the time the seed is ripe, the produce from 
the clayey loam is 

Grass, 19 oz. The produce per acre 206910 — 12931 14 

80 dr. of grass weigli when dry 36 dr. '> 

The produce of tlie space, ditto 136 3 1-5 5 ^^^^^ ^ "~ ^^^^ ^ * 
The weight lost by the produce of one acre in drying 7111 8 14 

64 dr. of grass afford of nutritive matter 1 1 dr. J) - 

The produee of the space, ditto 9. 975 V '''^ 4—461 



APPENDIX. IX. 

The weight of nutritive matter which is lost by leaving' the 
crop till the seed be ripe, being one twenty-fifth part of 
its value 17 8 11 

The proportional value which the grass at the 
time of flowering, bears to that at the time the seed is 
ripe, is as 6 to 9. 

The latter-math produce, from the clayey loam is 

oz. or lbs. per acre 
Grass, 12 oz. Tiie produce per acre 130680 — 8167 8 

64 dr. of grass afford of nutritive matter 2 dr. 

' 4083 12— 255 3 12 



Ir.S 



The pr duce of the space, ditto 6 dr 

The proportional value which the whole of the 
latter- math crop bears to that at the time the seed is 
ripe, is as 5 to 9, and to that at the time flowering, 
proportionably as 13 to 24. 

The above statement clearly shews that there is 
nearly three-fourths of produce greater from a clayey 
loam than from a sandy soil, and the grass from the lat- 
ter is comparatively of less value, in proportion as 4 
to 6. The straws produced by the sandy soil are defi- 
cient in number and in every respect less than those 
from the clayey loam ; which will account for the un- 
equal quantities of nutritive matter afforded by them ; 
but the proportional value in which the grass of the 
latter-math exceeds that of the crop at the time of 
flowering, is as 4 to 3; a difference which appears 
extraordinary, when the quantity of flower-stalks 
which are in the grass at the time of flowering is 
considered. In the Anthoxanthum odoratwn the pro- 
portional difference between the grass of these crops 
is still greater, nearly as 4 to 9 ; in the Foa praiensis 
they are equal; but in all the latter flowering grasses 
experimented upon, the flowering straws of which 

b 



X. APPENDIX. 

resemble those of the Alopecurus praiensis or Anthox' 
antbum odoratum, the greater proportional value is 
always on the contrary found in the grass of the 
flowering crop. Whatever the cause may be, it is 
evident that the loss sustained by taking the crops of 
these grasses at the time of flowering is considerable. 

V. Alopecurus alpinus. Engl. Bot. 1126. 
Alpine fox-tail grass. Nat. of Scotland. 

At the time of flowering the produce from a sandy 
loam with a small portion of manure, is 

oz. or lbs. per acre 

Grass, 8 oz. The produce per acre 87120 — 5445 5 
60 dr. of grass weigh when dry 16 dr. -^ 

The produce ofthe space, ditto 34 2-16 $ ^^'^'^'^ — 1452 

The weight lost by thf- produce of one acre in drying S993 5 
64 dr. of grass afford of nutritive matter 1 dr. -^ 

The produce of tht space, ditto 2 dr. 5 ^^^^ 4—85 1 4 

VI. Poa alpina. Engl. Bot. 1003. Flo. Dan. 107. 
Alpine meadow grass. Nat. of Scotland. 

At the time of flowering, the produce from a light 
sandy loam, is 

Grass, 8 oz. 1 he produce per acre 87120 — 5445 

64 dr.ofgi'ass afford of nutritive matter, 1.2 dr. 2041 14 — 127 9 14 

VII. Avena puhescem, Engl. Bot. 1640. Host. G. 
A. 2, t. 50. Downy oat grass. Nat. of Britain, 

At the time of flowering, the produce from a 
rich sandy soil, is 

Grass, 23 oz. The produce per acre 250470 — 15654 6 

80 dr. of grass weigh when dry 30 dr. ^ 

^1, A fi, V*; i"Q 1 f 93926 0— 5870 6 4 

The produce ofthe space, ditto 138 dr. 3 

The weight lost by the produce of one acre in drying 9783 15 12 

64 dr. of grass afford of nutritive matter 1. 2 dr. ^ ^ g 

The produce of tbc space, ditto 8.2 2-16 5 ^^'^^ ° "" 



APPENDIX, XI. 

At the time the seed is ripe, the produce is 

oz. or Ihs. per acre 

Grass, 10 oz. The produce per acre 108900 — 6806 4 

80 di*. oF grass weigh when dry 16 dr.") 

The produce ot the space, ditto 32 dr.i '^^^^° ^ ~ ^^^^ ^ 

The weigl I lost by the (reduce of one acre in drying — 5445 
64 Ir. of grass iifTord of nutritive matter 2 dr.-j 

Tlie produce of the space ditto 5 dr. 3 ^^^"^ ^ "" 212 11 

The weipht of nutritive matter which is lost by leaving the crop till the 

seed he- rip> , being' moiv than half of its value - 154 6 3 

The proportional value which the grass, at the 
time of flowering, bears to that at the time the seed is 
ripe, is as 6 to 8. 

The produce of latter-math is 

Grass, 10 oz i'he produce pi;r acre 108900 — 6806 4 

64dr.of grass afford of nutritive mutter 2 di'. 3403 2 — 212 11 

The proportional value which the grass at the 
time of flowering bears to that of the latter-math, is as 
6 to .8. The grass of the seed-crop, and that of the 
latter-math, are of equal value. 

The downy hairs which cover the surface of the 
leaves of this grass, when growing on poor light soils, 
almost entirely disappear when it is cultivated on a 
richer soil. It possesses several good qualities which re- 
commend it to particular notice; it is hardy, early, and 
more productive than many others which affect simi- 
lar soils and situations. Its growth after being cropped 
is tolerably rapid, although it does not attain to a great 
length if left growing; like the Poa pratensis it sends 
forth flower stalks but once in a season, and it appears 
well calculated for permanent pasture on rich light 
soils. 



xn. APPENDIX. 

VIII. Poa pratensis. Curt. Lond. Engl. Bot. 1073. 
Smooth stalked meadow grass. Nat. of Britain. 
At the time of flowering, the produce from a mix- 
ture of bog-earth and clay, is oz. or Ibs. per acre 
Grass, 15 oz. llie produce p r acre 163350 — 10209 6 
80 dr. ofgrass weigh when dry 22-2 dr. "> ^^^^^ ^_ ^sri 6 3 
The produce of the space, ditto 672 dr. 5 
The weight lost by the produce of one acre in drying 7337 15 13 

64 dr. of c-rass afford of nutritive matter 1.3 dr.") 

. ,■ . T.. /:c,iia\4465 2 — 279 2 9 

The produce of the space, ditto 0.2 1-lciJ 

At the time the seed is ripe, the produce is 

Crass, 12. 8 07.. The produce per acre 136125 — 85C7 13 

80 dr. ofgrass weigh when dry 32 dr.? ^^^^ ^__^^^„ ^ ^ 
The produce of the space, do 80 dr. J 

The weightiest by the produce of one acre in drying 5104 11 

64 dr. of 8:ra.ss afford of nutritive matter 12 dr. f 

1 f.i, Tf^ .io9iaC3190 6—199 6 

The produce of the space, ditto 4.2 3-163 

The weight of nutritive matter which is lost by leaving the 

crop till the seed be ripe, being nearly one fourth of its 

value - - 79 12 9 

The produce of latter-math is 

Gras.s 6 oz. 'I'he produce per acre 65340 — 4083 12 

64 dr. of Grass afford of nutritive matter 1.3 dr. 1786 10 — 111 10 

The proportional value in which the grass of the 
latter-math exceeds that of the flowering crop, is as 
6 to 7. The grass of the seed crop and that of the 
latter-math are of equal value. 

This grass is therefore of least value at the time 
the seed is ripe : a loss of more than one fourth of the 
value of the whole crop is sustained if it is not cut till 
that period: the straws are then dry, and the root 
leaves in a sickly decaying state; those of the latter- 
math, on the contrary, are luxuriant and healthy. 
This species sends forth flower-stalks but once in a 
season, and these being the most valuable part of the 
plant for the purpose of hay ; it will from this circum- 



APPENDIX. xiit. 

stance, and the superior value of the grass of the latter- 
math, compared to that of the seed crop, appear well 
adapted for permanent pasture. 

IX. Poa carulka, — Var. Foa pratens'u. Engl. Bot. 

1O04. Poa subcasrulea. Short blueish meadow- 
grass. Nat. of Britain. H. Kew. 1 — 155. Poa 
humilis. 

At the time of flowering, the produce from a soil 
of the like nature as the preceding, is 

oz. or lbs. per acre 

Grass, 11 oz. The produce per acre 119790 — 7486 14 

64 dr. of grass aiford of nutritive matter 2 dr. ^ 

The produce of the space, ditto 5.2 dr. 5 ^"^^^ ''"" ^^^ *^ ^ 

80 dr. of grass weigh when dry 24 dr. "^ 

The produce ofthe space, ditto 52.3 3-165 ^^^^'' ^ ~ 2246 1 

The weight lost by the produce of one acre in drying 5240 13 

If the produce of this variety be compared with 
that of the preceding one, it will be found less ; nor 
does it seem to possess any superior excellence. The 
superior nutritive power does not make up for the 
deficiency of produce by 80 lbs. of nutritive matter 
per acre. 

X. Festuca hordiformis. Poa hordiformis. H. Cant. 
Barley-like fescue grass. Nat. of Hungary. 

At the time of flowering, the produce from a sandy 
soil, with manure, is 

Grass, 20 oz. The produce per acre 217800 — 13612 8 

80 dr. of grass weigh when dry 24 dr. > 

The produce of the space, ditto 96 dr. \ ^^^40 - 4083 12 

The weight lost by the produce of one acre in drying 9528 12 

64 dr. of grass a,fr0rd of nutritive matter 2. 1 dr. 7 

The produce ofthe space, ditto 11. ldr.5 ^^^^ 0—478 9 

This is rather an early grass, though later than 
any of the preceding species j its foliage is very fine^ 



XIV. APPENDIX. 

resembling the F. duriuscula, to which it seems nearly- 
allied, differing only in the length of the awns, and the 
glaucous colour of the whole plant. The considera- 
ble produce it affords, and the nutritive powers it ap- 
pears to possess, joined to its early growth, are quali- 
ties which strongly recommend it to further trial. 

XI. Poa irhtalis. Curt. Lond. Engl. Bot. 1072, 
Host. G. A. 2. t. 62. Roughish meadow grass. 
Nat. of Britain. 
At the time of flowering, the produce from a light 

brown loam, with manure, is oz. or ibs. per acre 

Grass, 11 oz. The produce per acre 119790 — 7487 14 

80 dr. of erass weiprh when dry 24 dr. ■> 

^ , c.u A- J ^^oi^8 35937 — 2246 1 

The produce of the space, ditto 54 o-16 3 

The weight lost by the produce of one acit in drying 5240 13 

64 dr. of gr.>4ss afford of nutritive matter 2 dr. 7 

The p'oduceofthespce, ditto 5. 2 dr. J ^^'^^ '^ ~" 233 15 7 

At the time the seed is ripe, the produce is 

Grass, 11.8 uz. The proauce per acre 125235 — 7827 3 

80 dr. of grass weigh when dry 36 dr. 7 

J e.u A-./r. cooiifiS 56355 12 — 3522 3 12 

The produce of the space, ditto 823 3-16 J 

The weight lost by the produce of one acre in drying 4304 15 4 

64 dr. of grass afiFord of nutritive matter 2.3 dr. 7 

The produce of the space, ditto 7-3 3-53 

l"he weight of nutritive matter which is lost by taking the 
crop at the time of flowering, exceeding one fourth of its 
value 102 5 12 

The proportional value in which the grass of the 
seed crop exceeds that at the time of flowering is as 8 
to 11. 

The produce of latter-math is 

Grass, 7 oz. The produce per acre 76230 — 4764 6 

64 dr. of grass afford of nutritive matter 3 dr. 3573 4 — 223 5 4 

The proportional value by which the grass of the 
latter-math exceeds that of the flowering crop, is as 8 
to 12, and that of the seed crop as 1 1 to 12, 



APPENDIX. XV. 

Here then Is a satisfactory proof ©f the superior 
value of the crop at the time the seed is ripe, and of 
the consequent loss sustained by taking it when in 
flower; the produce of each crop being nearly equal. 
The deficiency of hay in the flowering crop, in propor- 
tion to that of the seed crop, is very striking. Its 
superior produce, the highly nutritive powers which 
the grass seems to possess, and the season in which 
it arrives at perfection, are merits which distinguish it 
as one of the most valuable of those grasses, which 
affect moist rich soils, and sheltered situations; but on 
dry exposed situations it is altogether inconsiderable j 
it yearly diminishes, and ultimately dies off, not un- 
frequently in the space of four or five years. 

XII. Festuca glauca. Curtis. 

Glaucous fescue grass. Nat. of Britain. 
At the time the seed is ripe the produce from a 

brown loam is oz. or Ibs. per acre 

Grass, 14 oz. The produce per acre 152460 — 9528 12 

80 dr. of grass weigh when dry 32 dr. ■> 

^u A f*u A*\ oooiiA< 60984 — 3811 8 

The produce of the space, ditto 89 2 1-16 > 

The weight lost by the produce of one acre in drying 5717 4 

64 dr. of grass afford of nutritive matter 1.2 dr. 7 

r^u 1 f*K a:. k^a CSSrS 4— 223 5 4 

The produce of the space, ditto 5.1 dr. y 

At the time of flowering the produce is 

Grass, 14 oz. The produce per acre 152460 — 9528 12 

80 dr. ofgrass weigh when dry ^2 dr ^ ^^^^^ ^ __ ^^^^ 3 ^ 
The produce of the space, ditto 89 2 2-53 

The weight lost by the produce of one acre in drying 5717 4 

64 dr. of grass afford of nutritive matter 3 dr. ? _, .- _ a»r. in o 
The produce of the space, ditto 10.2 dr. 5 

The weight of nutritive matter which is lost by leaving the 
crop till the seed be ripe, being half of the value of the 
crop .,.,...-• 223 5 5 



XVI. APPENDIX. 

TJie proportional value by which the grass at the 
time of flowering exceeds that at the time the seed is 
ripe, is as 6 to 1 2. 

The proportional difference in the value of the 
flowering and seed crops of this grass is directly the 
reverse of that of the preceding species, and affbrds 
another strong proof of the value of the straws in 
grass which is intended for hay. The straws at the 
time of flowering are of a very succulent nature; but 
from that period till the seed be perfected, they gradu- 
ally become dry and wiry. Nor does the root leaves 
sensibly increase in number or in size, but a total 
suspension of increase appears in every part of the 
plant, the roots and seed vessels excepted. The straws 
of the Poa irivialis are, on the contrary, at the time 
of flowering, weak and tender ; but as they advance 
towards the period of ripening the seed, they become 
firm and succulent; after that period, however, they 
rapidly dry up and appear little better than a mere dead 
substance. 

XIII. Festuca glabra. Wither. B. 2. P. 154. 
Smooth fescue grass. Nat. of Scotland. 

At the time of flowering, the produce from a clayey 

loam, with manure, is oz. or lbs. per acre 

Grass, 21 oz. The produce per acre 228690 0—14293 

80 dr. of erass weigh when dry 32 dr. f 

1 lie prodii ce of the space, ditto 134. 1 2-16 2-5 ) 

The weiglit lost by the produce of one acre in drying 8576 14 

64 dr. of eriiss afford of nulrltive matter 2 dr. ? 

MM 1 e.^ a:. -ioo » C ^146 0— 446 10 

T he produce oi tlie space, ditto 10.2 fir. 3 

At the time the seed is ripe the produce is 

Grass, 14 oz. The produce per acre 152460 — 9528 12 

80 dr. of grass weigli when dry 32 dr. 



r^x 1 <•*, r« Qoooei 60984 — 3811 8 

The produce of the space, ditto 89.2 2-5 



AP,PENDIXo XV IT 

oz. or lbs. per acre 
T!\e weight lost by the produce of one acre in drying 5717 4 

64 dr. of grass afford of nutritive matter 1. 1 dr. ) 

The produce of the space, ditto 4 12-16 3^^'^'' 0—186 1 

The weight of nutritive matter which is lost by leaving the 
crop till the seed be ripe exceedi:ighaif of its value 260 9 

The proportional value which the grass at the 
time the seed is ripe, bears to that of the crop at the 
time of flowering, is as 5 to 8. 
The produce of latter-math is 

Grass, 9 oz. The produce per acn- 98010 — 6125 10 

64 dr. of grass afford of nutritive matter 2 gr. ~\ 

The produce of the space, ditto 1.0l-2dr.3 765 11— 47 13 

The proportional value which the grass of the 
latter-math bears to that of the crop at the time of 
flowering, is as 2 to 8, and to that of the crop, at the 
time the seed is ripe, is as 2 to 5, 

The general appearance of this grass is very simi- 
lar to that of the Festuca duriuscula: it is, however, 
specifically different, and inferior in many respects, 
which will be manifest on comparing their several pro- 
duce with each other j but if it be compared with some 
others, now under general cultivation, the result is 
much in its favour, the soil which it affects being duly 
attended to. The A/itboxantbu7n odoratum being taken 
as an example, it appears, that 

Festuca glabra.^ affords of nutritive matter 

From the crop at the time of flowering 446. "> lbs. per acre 

At the time the seed is ripe, ditto 186. j °'32- 

Anthoxanthum odoratum^ 

At the time of flowering, ditto 122. 



^ > 433. 



At the time the seed is ripe, ditto 311. 

The weight of nutritive matter, which is afforded by the pro- 
duce of one acre of the Festuca glabra exceeding that of the 
i?ilhoxanihum odordimi, in proportion nearly as 6 to 9 199. 

C 



xvin APPENDIX. 

XIV. Festuca rubra. Wither. B. 2. P. 153. 
Purple fescue grass. Nat. of Britain. 

At the time of flowering, the produce from a h'ght 

sandy soil, is oz. or Ihs. per acre 

Grass, 15 oz. The produce per acre 163350 0—10209 6 

80 dr. of ffrass weie-li when dry 34 dr. 7 

'PI 1 f.u VM mo 1 C 5G923 12-3557 11 

The produce of the space ditto 102 ur 3 

The weight lost by the produce of one acre in drying 6651 11 

64 dr. of grass afford of nutritive matter 1.2 dr. ~) ^ 
The produce of the space, ditto 22 2-16 dr. 3 "^ 

At the time the seed is ripe, the produce is 

Grass, 16 oz. The produce per acre 174240 — 10890 

80 dr. of grass v.'eigh when dry 36 dr. 1 

The produceofthe space, ditto 115 3-16 dr. 5 ^'8408 0~ 4900 8 

The weight lost by the produce of one acre in drying 5989 8 

6 • dr. of grass afford of nulritivs matter 2 dr. ~) 

The produce of the space, ditto Sdr-i^^^^ 0—340 5 

The weight of nutritive matter which is lost by taking the 
crop when the grass is in flower, being nearly one third 
part of its value 101 8 

The proportional value which the grass, at the 
time of flowering, bears to that at the time the seed is 
ripe, is as 6 to 8, 

This species is smaller in every respect than the 
preceding. The leaves are seldom more than from 
three to four inches in length ; it affects a soil similar 
to that favourable to the growth of the Festuca ovitia, 
for which it would be a profitable substitute, as will 
clearly appear on a comparison of their produce with 
each other. 

The produce of latter-math is 

«ira'ss, 5oz. The produce pe r acre 54450 — 3403 2 

64dr, of grass afford of nutritive matter 1.2 dr. >]V>276 2 — 79 12 



APPENDIX. XIX 

The proportional value which the grass of the 
latter-math bears to that at the time the seed is ripe is 
as 6 to 8, and is of equal value with the grass at the 
time of flowering. 

XV. Festuca ovina. Engl. Bot. 585. Wither. B. 2, 
P. 152. Sheep*s fescue grass. Nat. of Britain. 

At the time the' seed is ripe, the produce is 

oz. or lbs. per acre 
Grass, 8 nz. The produce per acre 87120 — 5445 

64 dr. of glass afford of nutritive matter !.2 dr. "i 

The pr duce ot the space, ditto 3 dr. 5^03114— VJ7 9 

The produce of latter-math is 

Grass, 5 oz. The produce per acre 54450 — 3403 2 

64 dr. of ^rass yfford of nuttitive matter 1. 1 dr. 1063 7 — 66 7 7 

The dry weight of this species was not ascertained, 
because the smallness of the produce renders it entire- 
ly unfit for hay. If the nutritive powers of this species 
be compared with those, of the preceeding, the in- 
feriority will appear thus : 

Festuca ovi7ia, (as above) affords of nutritive matter 1.2> 
Ditto ditlo 1.1 i" ^'^ 

Festuca rubra ditto ditto ^ ^ o o 

ditto ditto ditlo 1.2 J 

The comparative degree of nourishment which 
the grass of the Festuca rubra affords, exceeds there- 
fore that afforded by the F. ovina ^ in proportion as 1 1 
to 14. 

From the trial that is here detailed, it does not seem 
to possess the nutritive powers generally ascribed to itj 
it has the advantage of a fine foliage, and may, there- 
fore, very probably be better adapted to the masticat- 
ing organs of sheep, than the larger grasses, whose 
nutritive powers are shewn to be greater: hence on 
situations where it naturally grows, and as pasture for 



XX APPENDIX. 

sheep, It may be Inferior to few others. It possesses 
natural characters very distinct from F. rubra, 

XVI. JBHza media. Engl. Bot. 340. Host. G. A. 
2. t. 29. Common quaking-grass. Nat. or 
Britain. 
At the time of flowering, the produce from a rich 

brown loam, is oz. or lbs. per acre 

Grass, 14 oz. The produce per acre 152460 — 9528 12 

83 cTr. of erass weierh wlien drv 26 dr. "> .. .. , ^ 

A r., r.f" ^otiiaC 49549 8 — 309613 S 

The produce of the space, ditto 72. 3 1-16) 

The weight lost by the produce of one ucre in drying 6431 14 8 

6idr. of erass afford of nutritive matter 2.3 dr. 7 

r 6551 — 409 7 
The produce of the space ditt'^ 9.2 2-16 J 

At the time the seed is ripe, the produce is 

t'jirass, 14 oz. The produce per acre 152460 — 9528 12 tt 

80 dr. of grass weigh when dry 28 dr. ") 

r 1 i-x. *fo 1 o £- S 5o0io2 — ooo5 I U 

The produce of the space, ditto 7o. 1 o-5 J 

The wcig'ht lost hy the produce of one acre in drying — 6183 11 

64 dr. of grass afford of nutritive matter 3.1 dr. | ^ 

The produce of the space, ditto 11. 1 1-2 j ' 

The weight of nutritive matter which is lost by taking the 

crop at the time of flowering, being nearly one-fourth 

part of its value 109 1 

The proportional value which the grass at the 
time of flowering, bears to that at the time the seed is 
ripe, is as 1 1 to 13. 

The latter-math produce is 

Crass, 12 oz. The produce per acre 130680 — 8167 8 

64 dr. of Grass afford of nutritive matter 2 di*. 4083 12 — 255 3 12 

The proportional value in which the grass at the 
time of flowering, exceeds that of the latter-math 
is as 8 to 11; and the latter-math stands to that at the 
time the seed is ripe in proportion as 8 to 1 3. 

The merits of this grass seem to demand notice ; 
jcs nutritive powers are considerable, and its produce 



APPENDIX. XXI 

large when compared with others whicli affect a similar 

soil. 

XVII. Dactylis glomerata. Engl. Bot. 335. Fl. 

Dan-. 743. Round-headed cock*s-foot grass. 

Nat. of Britain. Wither. B. 2. E. 149. 
At the time of flowering, the produce from a rich 

sandy loam, is oz. ur lbs. per acre 

Grass, 41 oz. Tlie produce per acre 446490 — 27905 10 

SO dr. of erass weigh when dry 34 dr. i 

TK. 1 ,.u vJ c-roA-i M89r58 — 11859 14 4 

The produce ot the space, ditto 278 4-.'j dr. j 

The weight lost by ihe produce of me acre in drying 16045 11 12 

6i dr. of crrass aftord of luitritive matter 2.2 dr. 7 ^ ^ ^ 

vh^r. 1 r*i tm o« 10^17424 — 1089 

ihe produce or the space, ditto 25.2 1-2-) 

At the time the seed is ripe the produce is 

tirass, ."9 oz. The produce per acre 424710 — 26544 6 

SO dr. of crass wei eh when dry 40 dr. 7 ^ ^ 

Ti ^ A <-*i v.. <5io 1 C 212355 — 13272 3 

The produce of the space, ditto 312 dr. j 

The weight lost by the produce of one acre in drying 13272 3 

64 dr. of grass afford of nutritive matter 3. 2 dr. - 

' 23226 5 — 1451 10 



. -^ cir. -\ 
,0 1-25 



The produce of the space, ditto 34. 

The weiglit of nutritive matter which is gained by leaving 
the crop till the seed be ripe, being more than one third 
part of its value, is - - - - - - 362 10 5 

The proportional value which the grass at the 
time of flowering, bears to that at the time the seed is 
ripe, is as 5 to 7, nearly. 

The produce of latter-math is 

Grass, 17 oz. 8 dr. The produce per acre 190575 — • 11910 15 
64 dr. of grass afford of nutritive matter 1.2 dr. 4466 9 — 281 10 9 

The proportional value which the grass of the 
latter-math bears to that at the time of flowering, is as 
6 to 10; and to that at the time the seed is ripe, as 6 
to 14. 64 dr. of the straws at the time of flowering 
afford of nutritive matter 1 .2 dr. The leaves or latter- 
math, and the straws simply, are therefore of equal 



XXII APPENDIX. 

proportional value; a circumstance which will point 
out this grass to be more valuable for permanent pas- 
ture than for hay. The above details prove, that a 
loss of nearly one third of the value of the crop is sus- 
tained, if it is left till the period when the seed is ripe, 
though the proportional value of the grass at that time 
is greater, /. e. as 7 to 5. The produce does not in- 
crease if the grass is left growing after the period of 
flowering, but uniformly decreases ; and the loss of 
latter- math, which, (from the rapid growth of the 
foliage after the grass is cropped) is very considerable. 
These circumstances point out the necessity of keep- 
ing this grass closely cropped, either with the scythe 
or cattle, to reap the full benefit of its great merits. 
XVIII. Brojims tectorum. Host. G. A. 1. t. 15. 

Nodding pannicled brome-grass. Nat. of 

Europe. Introduced 1776. H. K. 1. 168. 

At the time of flowering, the produce from a 

light sandy soil, is oz. or lbs. per acre 

Grass, 11 oz. The produce per acre 119790 — 7485 14 

80 dr. of grass weigh when dry 42 dr. 



The produce of the space, do 92.13-55 ^2889 12-3930 9 12 
The weight lost by the produce of one acre in drying 3556 4 4 

64 dr. of grass afford of nutritive matter 3 dr.' 



rr\ 1 f .1 r» o 1 ^ V 5615 2— 350 15 2 

The piouuce or the space, ditto o. 1 dr. 3 

This species being strictly annual, affords no 
latter-math, which renders it comparatively of little 
value. 

XIX. Fesiuca cambrka. Hudson. W. B. 2. P. 155, 

Nat. of Britain, 
At the time of flowering, the produce from a light 
sandy soil is 

Grass, 10 oz. The produce per acre 108900,0— 6806 4 

80 dr. ofgrass weigh when dry 34 dr. ") 

TK ^ 7 f^, 1-., po A C 46282 8—2892 10 8 

1 he produce Oi the ppace, dillo C8 or, 3 



APPENDIX. xxin 

oz. or lbs. per acre 

The weight lost by the produce of one acre inditing 3913 9 8 

64 dr. of grass afford of nutritive matter 2.1 dr. "> 

The produce of the space, ditto 5.2 1-23 ^^^^ ^ "" ^^^ ^' ^ 

This species is nearly allied to the Festuca ovina, 
from which it differs little, except that it is larger in 
every respect. The produce, and the nutritive matter 
which it affords, will be found superior to those given 
by the F. ovi?ia, if they are brought into comparison. 

XX. Bromus Diandrus, Curt. Lond. Engl. Bot. 1006, 

Nat. of Britain. 

At the time the grass is ripe flower, the produce 
from a rich brown loam, is 

Grass, 30 oz. The produce per acre 326700 0—20418 12 

80 dr. of grass weigh when dry 34dr."> 

The produce ofthe space, ditto 204 dr. 5 ^^^^^^ 8-8677 15 

The weight lost by the produce of one acre in drying 11740 13 

64 dr. of grass afford of nutritive matter 3 dr.") 

The produce ofthe spree, ditto 22.2 V^^^^ 1 — 957 2 1 

This species, like the preceding, is strictly annual; 
the above is therefore the produce for one year, which, 
if compared with that of the least productive of the 
perennial grasses, will be found inferior, and it must 
consequently be regarded as unworthy of culture. 

XXI. Poa angustifolia. With. 2. P. 142. 
Narrow-leaved meadow grass. Nat. of Britain. 

At the time of flowering, the produce from a brown 
loam, is 

Grass, 27 oz. The produce per acre 294030 — 18376 14 

80 dr. of grass weigh when dry 34 dr. ■) 

The produce of the space, ditto 183 2 2-51 ^24962 12 - 7810 2 12 

The weight lost by the produce of one acre in drying 10566 11 4 

64 dr. of grass afford of nutritive matter 5 dr. 7 

The produce of the space, ditto 333 5 22886 11-1430 6 11 



?:xiv APPENDIX. 

At the time the seed is ripe, the produce is 

Grass, 14 oz. The produce pt-r acre 152460 — 9528 12 

80 dr. of ffrass weiarli when dry 32 dr. > 

1 f , v» on oo,rt 60984 0— 3811 8 

The produce of the space, ditto 892 2-5 3 

The weight lost by the produce of one acre in drying 5717 4 

G4 dr. of ffrass aiTord of nutritive matter 5. 1 dr. ~) - 

1 f*i v., iciioC 12506 7 — 701 6 ^ 

Tlie produce of the space, ditto 18. 1 1-2 ) 

The weig-ht of nutritive matter which is lost by leaving the 

crop till the seed be ripe, exceeding one third part of its 

value 649 4 

In the early growth of the leaves of this species 
of Poa, there is a striking proof that early flowering 
in grasses is not always connected with the most abun- 
dant early produce of leaves. In this respect all the 
species which have already come under examination, 
are greatly inferior to that now spoken of. Before the 
middle of April the leaves attain to the length of more 
than twelve inches, and are soft and succulent; in 
May, however, when the flower-stalks make their ap- 
pearance, it is subject to the disease termed rust, 
which affects the whole plant; the consequence of 
which is manifest In the great deficiency of produce 
in the crop at the time the seed is ripe, being one-half 
less than at the time of the flowering of the grass. 
Though this disease begins in the straws, the leaves 
suffer most from its effects, being at the time the seed 
is ripe completely dried up; the straws therefore, 
constitute the principal part of the crop for mowing, 
and they contain more nutritive matter in proportion 
than the leaves. This grass is evidently most valua- 
ble for permanent pasture, for which, in consequence 
of its superior, rapid, and early growth, and the disease 
beginning at the straws, nature seems to have de- 
signed it. The grasses which approach uearest to thi'i 



APPENDIX. XXV 

in respect of early produce of leaves, are the Poa 

fertilise Dactylis glomerata, Phleum pratense^ Alopecurus 
^ratensisy Avena eliator, and Bromus littoreus, all 
grasses of a coarser kind. 

XXII. Avena eliator, Curtis 191. Engl Bot. 813. 
Holcus avenaceus. Tall oat-grass. Nat. of 
Britain,. 

At the time the seed is ripe, the produce is 

oz. or lbs. per acre 

Grass, 24 oz. The produce per acre 261360 — l6Zo5 
80 dr. of grass weigh when dry 28 dr. 7 

Theproduceofthespace, ditto 184.13-5 3 91475 14 — 5717 3 14 

The weight lost by the produce of one acre in drying 10617 12 2 

64 dr. of grass afford of nutritive matter 1 dr. 7 

c 4081 19 — "^55 *? 1" 
The produce of the space, ditto 6 dr. 3 ^^^^ *^ ^^^ -* ^- 

The produce of latter-math is 

Grass, 20 oz. The produce per acre 217800 — 13612 8 

64 dr. of Grass afford of nutritive matter 1.1 dr. 4253 14 — 265 13 14 
The weight of nutritive matter, which is afforded by the 
crop of the latter-math, exceeding that afforded by the 
grass of the seed crop in proportion nearly as 26 to 25 10 9 2 

This grass sends forth flower straws during the 
whole season; the latter-math contains nearly an equal 
number with the flowering crop. It is subject to the 
rust, but the disease does not make its appearance till 
after the period of flowering; it affects the whole plant, 
and at the time the seed is ripe the leaves and straws 
are withered and dry. This accounts for the superior 
value of the latter-math over the seed crop, and points 
out the propriety of taking the crop when the grass is 
in flower^ 

d 



x*:vi APPENDIX. 

XXIII. Poa eltaior, Curtis, 50. 

Tall meadow grass. Nat. of Scotland. 
At the time of flowering, the produce from a rich 

clayey loam is oz. or lbs. per acre 

Glass, 18 oz. The produce per acre 196020 — 12251 4 
80 dr. of grass weigh when dry 28 dr. ^ 

The produce of the space, ditto 100. 3 2-10 5 ^^^^"^ ° "~ ^"^'^ ^^ ^ 

64 dr. of grass afford of nutritive matter 3.2 dr ") i i " 

The produce of the space, ditto 15 3 3 ^°^^^ ^^ "~ ^^^ " "" 

The weight lost by the produce of one acre in drying 3517 15 3 

The botanical characters of this grass are almost 
the same as those of the Avena eliator, differing in the 
want of the awns only. It has the essential character 
of the Hold (Florets male, and hermaphrodite. Calyx 
husks two-valved with two florets) and since the 
Avejia eliator is now referred to that genus this may 
with certainty be considered a variety of it. 

XXIV. Festuca durimcula, Engl. Bot. 470. W. B. 
2. P. 153. Hard fescue grass. Nat. of 
Britain. 

At the time of flowering, the produce from a light 
sajidy loam is 

Grass, 27 oz. The produce per acre 294030 — 18376 14 

80 dr. of grass weigh when dry 36 dr. 7 

The produce of the space, ditto 194.13-53^^^^*^ ^~ ^^^^ ^ ^ 

The weight lost by the produce of one acre in drying 10106 4 B 

64 dr. of grass afford of nutritive matter 3.2 dr. 

The produce of the space, ditto 2G 

At the time the seed is ripe the produce is 

Grass, 28 oz. The produce per acre 304920 — 19075 8 

80 dr. of grass weigh when dry 36dr.-j 

The produce of the space, ditto 201.2 2-53 ^^^^^^ — 8575 14 

The weiglit lost by the produce of one acre in drying 1048110 

61 dr. of grass afford of nutritive matter 1. 2 dr. ^ 

Tiie produce of the space, ditio 1 0. 2 dr. \ ''^^^ 9 — 446 10 P 



3.2 dr. 7 
23 2 1.93 16079 12 — 1004 15 IS 



APPENDIX. xxvii 

oz. or lbs. per acre 
The weight of nutritive matter whieh is lost by leaving the 

crop till the seed be ripe exceeding one half of its value 558 5 3 

The proportional value which the grass at the 
time the seed is ripe, bears to that at the time of flower- 
ing, is as 6 to 14, nearly. 

The produce of latter-math is 

Grass, 15 oz. The produce per acre 163350 ^ 10209 6 

6^ dr. of grass afford of nutritive matter 1. 1 dr. 3190 4— 199 6 4 

The proportional value which the grass of the 
latter-math bears to that at the time of flowering, is as 
5 to 14, and to that at the time the seed is ripe, 5 to 6. 

The above particulars will confirm the favourable 
opinion which was given of this grass when speaking 
of the Festuca hordiformis^ and F. glabra. Its produce 
in the spring is not very great, but of the finest quali- 
ty, and at the time of flowering is considerable. If it 
be compared with those affecting similar soils such as 
Poa pratensis, Festuca ovina, Isfc. either considered as 
a grass for hay, or permanent pasture, it will be found 
of greater value. 

XXV. Bromus erectus, Engl. Bot. 471. Host. G. A. 
Upright perennial brome grass. Nat. of Bri- 
tain. 

At the time of flowering, the produce from a rich 
sandy soil is 

Grass, 19 02. The produce per acre 206910 — 1293114 

80 dr. of grass weigh when dry 36 dr. -j 

The produce ofthe space, do 136.3 1-55 93109 8 — 5819 5 6 

The weight lost by the produce of one acre in drying 7112 8 8 

64 dr. of grass afford of nutritive matter 2.3 dr. > 

The produce of the space, ditto 13. 1-4 $ ^^^° ^° "" ^^^ ^° *° 



XXVIII APPENDIX. 

XXVI. Milium effusum. Curt. Lon. Engl. Bot. 1 106. 
Common millet grass. Nat. of Britain. 
At the time of flowering, the produce from a light 

sandy soil is oz. or lbs. per acre 

Grass, 11 oz. 8 dr. The produce per acre 196020 — 12251 4 
80 dr. of grass weigh when dry 31 dr. " 



v» til oofiV 75957 12-4747 5 12 
The produce of the space, ditto 111. 2 2-6 3 

64 dr. of grass afford of nutritive matter 1. 3 dr. ^ ^^ .. 

n^. 1 f,u A^*^^ - 09. C 5359 14— (334 15 14 

The produce 01 the space, ditto 7. o ■i-'t j 

This species in its natural state seems confined to 
woods as its place of growth; but the trial that is here 
mentioned, confirms the opinion that it will grow and 
thrive in open exposed situations. It is remarkable 
for the lightness of the produce, in proportion to its 
bulk. It produces foliage early in the spring in con- 
siderable abundance; but its nutritive powers appear 
comparatively little. 

XXVII. Festuca pratensis, Engl. Bot. 1592. C. Lond. 
Meadow fescue grass. Nat. of Britain. 

At the time of flowering, the produce from a bog 
soil, with coal ashes for manure, is 

Grass, 20 oz. The produce per acre 217800 0—13512 8 

80 dr. of crass weigh when dry 38 dr. "> 

rr^u A r^K A-,, 1MJ \ 103455 8 — 6465 15 

The produce of the space, ditto 152 dr. J 

The weight lost by the produce of one acre in drying .— 7146 9 

64 dr . of g^ass afford of nutritive matter 4 .2 dr. 7 

The produce ofthe space ditto 22.2 dr. V^'^^'* 1— 957 2 1 

At the time the seed is ripe, the produce is 

Grass, 28 oz. The produce per acre 304920 — 190S7 8 

80 dr. of grass weigh when dry 32 dr. ' 



The produce of the space ditto 179.0 4-5'' ^^^^^^ — 7623 
The weight lost by the produce of one acre in drying 11434 8 

64 dr. of grass aflPord of nutritive matter 
Tho produce of the space, ditto 10.2 

The weight of nutritive matter which Is lost by leaving the 
crop till the seed be ripe, exceeding one half of its value 510 7 



1.2 dr. 7 
10.2 dr. r"^ 9-446 10 9 



APPENDIX. XXIX 

The value of the grass at the time the seed is 
ripe, is to that of the grass at the time of flowering, 
as 6 to 1 8. 

The loss which is sustained by leaving the crop 
of this grass till the seed be ripe is very great. That 
it loses more of its weight in drying at this stage of 
growth, than at the time of flowering, perfectly agrees 
with the deficiency of nutritive matter in the seed crop, 
in proportion to that in the flowering crop: the straws 
being succulent in the former, they constitute the 
greatest part of the weight; but in the latter they are 
comparatively withered and dry, consequently the 
leaves constitute the greatest part of the weight. It 
may be observed here, that there is a great difference 
between straws or leaves that have been dried after 
they were cut in a succulent state, and those which 
are dried (if I may so exprees it) by nature while 
growing. The former retain all their nutritive powers; 
but the latter, if completely dry, very little, if any. 

XXVIII. Lolium perenne, Engl. Bot. 315. Flo. 
Dan. 747. Perennial rye-grass. Nat. of 
Britain. 

At the time of flowering, the produce from a rich 
brown loam, is 

oz. or lbs. per acre 
Grass, 11 oz. 8 dr. The produce per acre 125235 — 7827 3 

80 dr. of erass weiprh when dry 34 dr. ^ 

^ '3156 13 — 3322 4 1^ 



,^531 



The produce of the space, ditto 78 4-10. 

The weight lost by the produce of one acre in drying 4494 14 

64 dr. of grass afford of nutritive matter 2.2 dr. 



The produce of the space, ditto 7.0 3-43 ^^^^ ^^^ ^°^ ^^ ^^ 

At the time the seed is ripe, the produce is 

Grass, 22 oz. The produce per acre 239580 — 14973 12 C 



XXX APPENDIX. 

oz. or lbs. per acre 
8Ddr.ofgrasswe^ghwhendn^ 24dr "> ^^^^^ o - 4492 2 
The produce of the space, ditto 105.2 2-5 j 

The weight lost by the produce of one acre in drying 1048110 

64 dr. of grass afford of nutritive mattef 23 dr. 7 

The produce of the space, ditto 15 2-16 P^^^'* 7—643 6 7 

The weight of nutritive matter which is lost by taking the 
crop at the time of flowering, nearly one half its value 337 8 8 

The proportional value which the grass at the 
time of flowering, bears to that at the time the seed is 
ripe, is as 10 to 11. 

The produce of latter-math is 

Grass, 5 oz. The produce per acre 54450 — 3403 2 

64dnof grass aflford of nutritive matter 1 dr. 850 12 — 53 2 12 

The proportional value which the grass of the 
latter-math bears to that at the time of flowering, is as 
4 to 10, and to that at the time the seed is ripe, as 4 
to 11. 

XXIX. Poa marttima. Engl. Bot. 1140. 
Sea meadow grass. Nat. of Britain. 

At the time of flowering, the produce from a light 
brown loam is 

Grass, 18 oz. The produce per acre 196020 — 12251 4 

80 dr. of grass weigh when dry 32 dr. ^ 

The produce of the space, ditto 115. 1-5 5 ^^^^^ ^ - ^^°° ^ ° 

'J lie weight lost by the produce of one acre in drying 7350 4 

&■% dr. of grass afford of nutritive matter 4. 2 dr. ^ 

The produce of the space, ditto 20. 1 dr. 5 ^^^^^ — 861 6 

The produce of latter-math is 

€r«ss, 18 oz. The produce per acre 196020 — 12251 4 

(Mdr.ofgrass afford of nutritive matter, 1 dr. 3062 13 — 191 6 31 

The proportional value which the grass of the 
latter- math, be^rs to that at the time of flowering, is 
as 4 to 18. 



dr.l 
, V 29403 — 1837 11 



APPENDIX. 3txxi 

XXX. Cynosurus cristatus. Engl. Bot. 316. Host. 
G. A. 2. t. 96. Crested dog's-tail grass. 

At the time of flowering, the produce from the 
brown loam, with manure, is ©z. or lbs. per acre 

Grass, 9 oz. The produce per acre 98010 — 6125 10 

80 dr. of grass weigh when dry 24 ' 

The produce of the space, ditto 43 

The weight lost by the produce of one acre in drying 4287 15 

64 dr. of grass afford of nutritive matter 4.1 dr. > 

The produce ofthc space, ditto 9.2 1-165^^°^ ^"^ 406 12 7 

At the time the seed is ripe, the produce is 

Gr.'>ss 18 oz. The produce per acre 196020 — 12251 4 

80 dr. of grass weigh when dry 32 dr. 7 

Tu A e.u r« ii-inaini 78408 — 4900 

The produce of the space, ditto 115.0 8-10 -* 

The weight lost by the produce of one acre in drying 7350 12 

64 dr. of grass afford of nutritive matter 2.2 dr. ~\ 

The produce ofthe space, ditto 11.1 dr.j "^^^"^ — 478 9 

The weight of nutritive matter which is lost by taking the 
crop at tlie time of flowering, exceeding one sixth of its 
value 71 12 9 

XXXI. Avena pratensis Engl. Bot. 1204. Fl. Dan. 
1083. Meadow oat-grass. Nat. of Britain. 

At the time of flowering, the produce from a rich 
sandy loam, is 

Grass, 10 oz. The produce per acre 108900 — 6806 4 

80 dr. of grass weigh when dry 22 dr." 

The produce of the space, ditto 44 ^ 

The weight lost by the produce of one acre in drying 4934 8 8 

64 dr. of grass afford of nutritive matter 2. 1 dr. ■> 

The produce ofthe space, ditto 5. 2 1-2 j 

At the time the seed is ripe, the produce is 

Grass, 14 oz. The produce per acre 152460 — 9528 12 

80 dr. ofgrass weigh when dry J^dr.^ 0-2858 10 

The produce of the space ditto 67.0 4-5> 

The weight lost by the produce of one acre in drying 6670 2 

64 dr. of grass afford of nutritive matter 1 dr. ' 

The produce ofthe space, ditto 



^^^ 29947 8 — 1871 11 8 



ldr.7 



XXXII APPENDIX. 

oz. or lbs. per acre 

The weight of nutritive matter which is lost by leaving the 

crop till the seed be ripe, exceeding one third part of its 

value ^ . V go, ,§ 

The proportional value which the crops, at the 
time the seed is ripe, bear to that at the time of flower- 
ing, is as 4 to 9. 

XXXIII. Bromus mult'iflorus. Engl. Bot. ISS'^-. Host, 
G. A. 1. t. II. Many flowering brome- 
grass. Nat. of Britain. 

At the time of flowering, the produce front a clayey- 
loam, is 

Grass, 33 oz. The produce per acre 359370 — 22460 10 

80 dr. of grass weigh when dry 44 dr." 



The produce of the space ditto 290.0 2-5> 19^^53 8 — 12353 5 8 



The weight lost by the produce of one acre in drying 10107 4 8 

64 dr. of grass afford of nutritive matter 5 dr.-) 

ri, A e.u Au. All A f 28075 12—1754 U 12 

The produce 01 the space, ditto 41.1ur.j 

This species is annual, and no valuable proper- 
ties have as yet been discovered in the seed. It is 
only noticed on account of its being frequently found 
in poor grass lands, and sometimes in meadows. It 
appears from the above particulars to possess nutritive 
powers equal to some of the best perennial kinds, if 
taken when in flower; but if left till the seed be ripe 
(which, from its early growth, is frequently the case), 
the crop is comparatively of no value, the leaves and 
straws being then completely dry. 



APPENDIX. xxxiii 

XXXIII. Festuca loUacea, Curt. Lond. Engl. Bot. 
1821. Spiked fescue grass. Nat. of Bri- 
tain. 
At the time of flowering, the produce from a brown 

rich loam, is oz. or Ibs. per acre 

Grass, 24 oz. The produce per acre 261360 — 16335 

SO dr. of grass weigli wlien dry 35 dr. "> 

The produce of the spuce, do 168 dr.5 ^^^'^^^ 0-7146 9 

The weight lost by the produce of one acre in drying 9188 7 

64 dr. of grass afford of nutritive matter 3 dr. f 

The produce of the space, ditto 18 dr. J ^^251 4 — 765 11 C 

At the time the seed is ripe, the produce is 

Grass, 16 oz. The produce per acre 174240 — 10890 

SO dr. of grass weigh when dry 33 dr. ^ 

The produce of the space, ditto 105 3-5 dr.5 ''^^'''^ ^~ ^^^^ ^ ^ 

The weight lost by the produce of one acre in drying 6397 14 

64 di\ of grass afford of nutritive matter 3. 1 dr. ) 

The produce of the space, ditto 13 dr. 5 ^^^^ 2 — 553 2 

The latter-math produce is 

(irsss, 5 oz. The produce per acre 54450 — 3405 2 

64dr.of grass afford of nutritive matter, 1.1 dr. 1063 7 — 66 7 7 
The weight of nutritive matter which is lost by leaving the 
crop till tlie seed be ripe, exceeding one fourth part of its 
value - .... . - 212 11 

The proportional value which the grass, at the 
time of flowering, bears to that at the time the seed is 
ripe, is as 12 to 13; and the value of the latter-math 
stands in proportion to that of the crop at the time of 
flowering, as 5 to 1 2, and to that of the crop taken at 
the time the seed is ripe, as 5 to 13, 

This species of fescue greatly resembles the rye 
grass, in habit and place of growth; it has excellencies 
which make it greatly superior to that grass, for the 
purposes of either hay or permanent pasture. This 
species seems to improve Jn produce in proportion of 

e 



3CXXIV APPENDIX. 

its age, which is directly the reverse of the Lolium 

perenne, 

XXXIV. Poa cristata. Host. G. A. 2. t. 75. — Aira 

Cristata. Engl. Bot. 648. Crested meadow 

grass. Nat. of Britain. 

At the time of flowering, the produce from a sandy 

loam, IS oz. or lbs. per acre 

Grass, 16 oz. The produce per acre 174240 — 10890 

80 dr. of crrass weicrh when dry 36 dr.-) 

TK 1 f.i v.. ii^oiA? ^^848 — 4900 8 

k he protluce of the space ditto 115 o-lo 3 

The weight lost by the produce of one acre in drying 5989 8 

64 dr.oFgra«s afford of nutritive matter 2 dr. ' 



The produce of the space, ditto 8 dr. 5 ^^^^ — 340 5 

The produce of this species, and the nutritive 
matter that it affords, are equal to those of the Festuca 
ovina at the time the seed is ripe; they equally delight 
in dry soils. The greater bulk of grass in proportion 
to the weight, with the comparative coarseness of the 
foliage, render the Poa cristata inferior to the Festuca 
ovina. 
XXXV, Festuca myurus. Engl. Bot. 1412. Host. 

G. A. 2. t. 93. Wall fescue grass. Nat. 

of Britain. 
At the time of flowering, the produce from a light 
sandy soil is 

Grass, 14 oz. The produce per acre 152460 



\^ 45738 



— 9528 12 





— 2858 10 





6670 2 





4-- 223 5 


4 



The produce of the space, ditto 67 2-10, 

The weight kst by the produce of one acre in drying 
64 dr. of grass afford of nutritive JWitter 1. 2 dr.-^ 
The produce of the space, ditto 5.1 dr. 3 

This species is strictly annual ; it is likewise sub- 
ject to the rust; and the above being its whole pro- 
duce for one year, it ranks as a very inferior grass. 



APPENDIX. xxxT 

XXXVI. Airo flexuosa* Engl, Bot. 1519. Host. G. 
A. 2. t. 43. Waved mountain hair-grass. 
Nat. of Britain. 

At the time of flowering, the produce from a heath 

son, IS Qz. or lbs. per acre 

Gr»ss, 12oz. The produce per acre 130680 0— 81&7 8 

SO dr. of grass weigh when dry 31 ilr"^ 

The produce ofthe space, ditto 'M 2-5> ^^^^^ — 3154 14 8 

The weight lost by the produce of one acre in drying 5002 9 8 

64 dr. of grass afford of nutritive matter 1. 2 dr.-j 

The produce of the space, ditto 4. 2 dr. 5 ^^^^ ^^ "" ^^^ ^ ^^ 

XXXVII. Hordeum bulbosutn. Hort. Kew. 1. P. 179. 
Bulbous barley grass. Nat. of Italy and 
the Levant. Introduced 1770, by Mons. 
Richard. 

At the time of flowering, the produce from a 
clayey loam with manure, is 

Grass, 35 oz. The produce per acre 381150 —■ 23821 

80 dr. of grass weigh when dry 93dr.^ 

The produce of the space, ditto 231 dr j ^^''^^'^ ° "~ ^^^^ ^ ^ 

The weight lost by the produce of one acre in drying 13994 7 10 

64 dr. of grass afford of nutritive matter 3.2 dr. ^ 

The pro.luce of the space, ditto 30.2 2^5 ^^^^^ ^ "" '^^^^ ^^ ^ 

XXXVIIL Festuca calamaria. Engl. Bot. 1005. 

Reed-like fescue grass. Nat. of Britain. 

At the time of flowering, the produce from a clayey 
loam is 

Crass, 80 oz. The produce per acre 8n200 — 54450 

80 dr. of grass weigh when dry 28 dr.l 

The produce of the space, ditto 448 dr.) ^04920 0-19057 8 

The weightiest by the produce of one acre JA drying 35392 8 

64 dr. of grass afford of nutritive matter 4.2 dr.'^ 

The produce ofthe spa«^, ditto 90dr.3^^256 4-3828 8 4 



xxxYi APPENDIX. 

At the time the seed is ripe, the produce is 

oz. or lbs. per aci^ 
Grass, 75 oz. The produce per acre 816750 — 51046 14 

80 dr. of grass weigh when dry 19 dr. ~J 

TJie produce of the space, ditto 283 dr. 3 ' ^^^^^ ^ - 12123 10 

The weight lost by the produce of one acre in drying 38923 4 

64 dr. of trrass afl'ord of nutritive matter 3 dr. 7 

n-, 1 *■*, r.. -t« 1 C 38285 2 — 2392 13 ? 

1 he produce or the space, cUlto So. 1 ■> 

The weig-ht of nutritive matter which is lost by leaving the 

crop till the seed be ripe, being nearly one third part of 

iis value 1435 11 2 

The proportional value which the grass at the 
time the seed is ripe, bears to that at the time of flower- 
ing, is as 1 2 to 18. 

This grass, as has already been remarked, pro- 
duces a fine early foliage in the spring. The produce 
is very great, and its nutritive powers are considerable. 
It appears from the above particulars, to be best adapt- 
ed for hay. A very singular disease attacks, and 
sometimes nearly destroys the seed of this grass; the 
cause of this disease seems to be unknown; it is de- 
nominated Clavus by some; it appears by the seed 
swelling to three times its usual size in length and 
thickness, and the want of the carcle. Dr. Willdenow 
describes two distinct species of it; 1st, the simple 
clavus, which is mealy and of a dark colour, without 
any smell or taste; 2nd, the malignant clavus, which 
is violet blue. Or blackish, and internally too has a 
blueish colour, a foetid smell, and a sharp pungent 
taste. Bread made from grain affected with this last 
species, is of a blueish colour; when eaten produces 
cramps and giddiness. 



APPE'NDIX. xxxvn 

XXXIX. Bromus Uttoreus. Host. G. A. P. 7. t. 8. 
Sea-side brome grass. Nat. of Germany, 
grows on the banks of the Danube and 
other rivers. 

At the time of flowering, the produce from a clayey 

loam is oz. oi- lbs. per acre 

Grass, 61 oz. The produce per acre 664290 — 41518 2 

80 dr. of grass weigh when dry 41 dr. | ^^^^^^ ^^_^^^^^ ^ ^^ 

1 he produce oi the space, ditto 500 2-10 j 

The weight lost by the produce of one acre in drying 20540 1 6 

64 dr. of grass aflbrd of nutritive matter 1.2 dr.-) 

The produce of the space, ditto 22.3 1-23 ^^^^^ ^"" ^''^ ^ ^ 

At the time the seed is ripe the produce is 

Grass, 56 oz. The produce per acre 609840 — 38115 

80 dr. of grass weigh when dry 32 dr.-* 

„., , f^. „ ,.,, n/reifiC 243936 — 15246 

The produce of the space, ditto 358 1-63 

The weight lost by the produce of one acre in drying 22869 

64 dr. of grass afford of nutritive matter 3.2 dr. 7 

The produce of the space, ditto 196 3 ^T^^^ 0-2084 6 10 

The weight of nutritive matter which is lost by taking the 
crop at the time of flowering, exceeding one half of its 
value - 1111 5 6 

The proportional value which the grass at the 
time of flowering, bears to that at the time the seed is 
ripe, is as 6 to 14. 

This species greatly resembles the preceding in, 
habit and manner of growth; but is inferior to it in 
■ value, which is evident from the defiiciency of its pro- 
duce, and of the nutritive matter afforded by it. The 
whole plant is likewise coarser and of greater bulk in 
proportion to its weight. The seed is affected with 
the same disease which destroys that of the former 
species. 



XXXVIII APPENDIX. 

XL* Festuca eliafor. Engl. Hot. 1593. Host. G. A, 
2. t. 79. Tall fescue grass. Nat. of Britain. 
At the time of flowering, the produce from a black 

riCfl loam, is oz. or Ibs. per acre 

Grass, 75 uz. The produce per acre 816750 — 51046 14 

80 dr. of grass wei^h when dry 28 dro 

^, , r.i ^ J-./ ^oA 1 e 285852 8—17866 6 8 

Tlic produce of the space, ditto 420 dr. 3 

The weight lost by the produce of one acre m drying 33180 7 8 

64 dr. of grass afford of nutritive matter 5 dr. ^ 

The produce of the space, ditto 93.3 5 63808 9-3988 9 

At the time the seed is ripe, the produce is 

Crass, 75 oz. The produce per acx-e 816750 — 51046 4 

80 dr. of grass weigh when dry 28 dr." 



The produce of Uie space ditto 420 dr. 3 ^^^^^^ 8-17866 6 

The weight lost by the produce of one acre in drying 33180 7 8 
64 dr. of grass afford of nutritive matter 3 dr. 7 

The produce of the space, ditto 56.1 3^^^^^ 2 — 2392 13 2 

The weight of nutritive matter which is lost by leaving the 
crop till the seed be ripe, exceeding one third part of its 
value 1595 3 7 

The proportional value which the grass at the 
time the seed is ripe, bears to that at the time of flower- 
ing, is as 12 to 20. 

The produce of latter-math is 

Grass, 23 oz. The produce per acre 250470 — 15654 6 

64 dr. of Grass afford of nutritive matter 4 dr. 15654 6 — 978 6 6 

The proportional value which the grass of the 
latter-math bears to that of the crop, is as 16 to 20; 
and to that at the time the seed is ripe, as 12 to 16, 
inverse. 

This species of fescue is closely allied to the FeS" 
tiica pratensis, from which it differs in little, except 
that it is larger in every respect. The produce is near- 
ly three times that of thje F, pratensis, and the nutritive 



APPENDIX. XXXIX 

powers of the grass are superior in direct proportion, 
as 6 to 8. 

XLI. Nardus strict a. Engl. Bot. 290. Host. G. A, 
2. t. 4. Upright mat-grass. Nat. of Britain. 
At the time the seed is ripe, the produce is 

oz. or lbs. per acre 
Grass, 9 oz. The produce per acre 98010 — 6125 10 

80 dr. of ffrass weigh when dry 32 dr. J 

* 39204 — 2450 4 



2-5 5 



The produce of the space, ditto 57 2 2- 

The weight lost by the produce of one acre in drying 3675 6 

64 dr. of grass afford of nutritive roatter 2.1 dr. 7 ... „ .,« 

rr, J f.u j-.x ent ^f 3445 10— 215 5 10 

The produce or the space, ditto 5.0 1-5 3 

XLII. Triticum, Sp» 
Wheat-grass. 
At the time of flowering, the produce from a rich 
sandy loam, is 

Crass, 18 oz. The produce per acre 196020 — 12251 4 

80 dr. of grass weigh when dry 32 dr. 



rp] .A c.u V*. -iieir V 78408 — 4900 8 

The produce of the space, ditto 115 1-5 j 

The weight lost by the produce of one acre in drying 7350 12 

64 dr. of grass afford of nutritive matter 2.2 dr. ) 

-^u 1 f.i 1*^ 111^ C7'657 0—478 9 

Th produce of the space, ditto 11.1 dr. 3 

XLIII. Festucafluitans, Curt. Lond. Engl. Bot. 1520. 
Poa fluitans. Floating fescue grass. Nat. of 
Britain. 

At the time of flowering, the produce from a strong 
tenacious clay, is 

Gri.ss, 20oz. The produce per acre 217800 — 13612 8 

80 dr. of grass weigh when dry 24 dr. ") 

rru A P.u A- J of^A f 65340 0—4083 12 

The produce of the space, ditto 96 dr. J 

The weight lost by t'he produce of one acre in drying 9528 12 

64 dr. of grass afford of nutritive matter 1.3 dr. > 

rru A f.K v.. o"j C5955 0— 372 3 7 

The produce of the spacf, ditto 8.3 dr. ) 

The above produce was taken from grass that 
had occupied the ground for four years, during which 



xl APPENDIX. 

time it had increased every year; it therefore appeals 
contrary to what some have supposed to be capable of 
being cuhivated in perennial pastures. 

XLIV. Holciis lanatus. Curt. Lond. Fl. Dan. 1181. 
Meadow soft grass. Yorkshire grass. Nat. 
of Britain. 

At the time of flowering, the produce from a strong 

clayey loam, is / oz, or ibs -v, acre 

Grass, 28 oz. The produce per acre 304920 0—19057 8 

80 dr. of grass weigh when dry 26 dr. 



•.^^ oocv 106585 14— 6661 9 14 
Uie produce of the space, ditto 157. 2 2-5 . 



The weight lost by the produce of one acre in drying 12395 14 2 

64 dr. of grass afford of nutritive matter 4 dr. ^ 

The produce of the space, ditto 28 dr. 5 ^'^^^^ 8—1191 1 8 

At the time the seed is ripe, the produce is 

Grass, 28 oz. The produce per acre 504920 — 19057 8 

80 dr. of sjrass weiph when dry 16 dr."> 

1 P.I v.; onoo^^ 60984 — 3811 8 

1 he produce or the space, ditto 89. 2 2-5 J 

The weight lost by the produce of one acre in drying 15246 

64 dr. of errass afford of nutritive matter 2.3 dr. ? . . „ 

1 f., A-., mil M3102 0—81814 

1 he produce of the space, ditto 19. 1 dr. 3 

The weifjht of nutritive matter which is lost by leaving the 
crop till the seed be ripe exceeding one third part of its 
value 372 3 8 

The proportional value which the grass at the 
time the seed is ripe, bears to that at the time of flower- 
ing, is as 1 1 to 1 2. 
XLV. Fesiuca du7netorum. Flo. Dan. 700. 

Pubescent fescue grass. Nat. of Britain. 
At the time of flowering, the produce from a black 
sandy loam, is 

Grass, 16 oz. Tlie pro-luce per acre 174240 — 10890 

80 dr. of ffcass weigh wjien dry 40 dr. "| 

■^ ^ ^ \ 87120 ..- 5445 

Tiic produce of the space, ditto 128 dr. J 



APPENDIX. xlj 

02. or ib3. per acre 

The weight lost by the produce of one acre in drying 5445 
64 dr. of grass afford of nutritive matter 1 di-. ) 

The produce of the space, ditto 4 dr. J "''^^ 8—170 2 8 

XLVL Poa fertilise Host. G. A. 

Fertile meadow grass. Nat. of Germany. 

At the time of flowering, the produce from a clayey 
loam, is 

Grass, 22 oz. The produce per acre 239580 0—14973 12 

80 dr. of grass weigh when dry 42 dr. 



The produce of the space, ditto 184 4-5 dr. i ^25779 8 — 7861 3 8 

The weight lost by the produce of one acre in drying 7111 8 8 

64 dr. of grass afford of nutritive matter 4.2 dr. > 

The produce of the space, ditto 24.3 5 ^^'^'^^ 7 — 1052 13 7 

If the nutritive powers and produce of this species, 
be compared with any other of the family, or such as 
resemble it in habit and the soil which it affects, a 
superiority will be found, which ranks this as one of 
the most valuable grasses; next to the Poa angustifolia^ 
it produces the greatest abundance of early foliage, of 
the best quality, which fully compensates for the com'- 
parative lateness of flowering. 

XLVII. Arundo color ata, Hort. Kew. I. P. 174, 
Engl. Bot. 402. Phalaris arundinacea. 
Striped-leaved reed grass. Nat. of Britain, 
At the time of flowering, the produce from a black 

sandy loam, is 

Grass, 40 oz. The produce per acre 4356D0 — 27225 

80 dr. of grass weigh when dry 36 dr. ^ 

The produce of the space, ditto 288 dr. J ' ^^^^° ° "~ -^^^^^ ^ ^ 

64 dr. of grass afford of nutritive matter 4 dr. 7 

The produce of the space, ditto 40dr.3 2''225 0—1701 9 

The strong nutritive powers which this grass 
possesses recommend it to the notice of occupiers of 

f 



^ ] 196020 — 12251 

e ii 

.2 •> 

^^. j 30628 2 — 1914 4 2 



xki APPENDIX. 

strong clayey lands, which cannot be drained. Its 
produce is great, and the foliage will not be denomina- 
ted coarse, if compared with those which afford a pro- 
duce equal in quantity. 

XLVIII. Trifolhun pratense. W. Bot. 3. P. 137. 
Broad-leaved cultivated clover. Nat. of 
Britain, 

At the time the seed is ripe, the produce from a 

rich clayey loam, is .,z. or lbs. per acre 

Grass, 72 oz. The produce per acre 7840S0 — 49005 

80 dr. of grass weigh when dry 20 dr. 

The pi-oduce of the space, ditto 288 Or.. 

The weight lost by the produce of one acre in dryuig 3675 4 

64 df . of grass afford of nutritive matter 2.2 
The produce of the space, ditto 45 

If the weight which is lost by the produce of this 
species of clover, in drying, be compared with that of 
many of the natural grasses, its inferior value for the 
purpose of hay, compared to its value for green food, 
or pasture, will appear; for it is certain that the diffi- 
culty of making good hay increases in proportion with 
the quantity of superfluous moisture which the grass 
may contain. Its value for green food, or pasture, 
may further be seen by comparing its nutritive powers, 
with those manifested by other plants generally esteem- 
ed best for this purpose. 

Trifolium pratense (.as above) affords of nutritive matter 2.2 dr. 
J[L1X. Trifolium repens (white clover) from an equal quantity 

of grass 20 dr 

L. Ditto, variety, with brown leaves, ditto 2.2 dr. 

The grass of the T. pratense, therefore, exceeds in 
^-alue that of the T. repens, by a proportion, as 8 to 10; 



APPEMDIX. xhii 

but it is of equal proportional value with the brown 
variety. 

LI. Burnet (Poteriiim sanguisorba) affords of nutritive matter 22 dr. 
LII. Buniaa orientalis, (a newly uilroduced plant), ditto 2.2 dr. 

The proportional value of these two last, and of 
the T. pratense^ and the brown-leaved variety of T, 
repens, are equal: they exceed the T. repens, as 8 to 10. 

The comparative produce of these four last men- 
tioned specieg, per acre, has not been ascertained...- 
LIII. Trifolium macrorhi'zunu 

Long-rooted clover. Nat. of Hungary. 

At the time the seed is ripe, the produce from a rich 

clayey loam, is oz. or lbs. per acre 

Grass. 144 oz. The produce per acre 1568160 0—- 98010 

80dr. of grass weigh when dry 34 dr. 7 ..-..„ . ^ic-^ / n 

The produce of the space, ditto 979 1-5 3 

The weight lost by the produce of one acre in drying 56355 12 

64 dr. of grass afford of nutritive matter 2.o dr.^^ 

The produce of the space, ditto 99 dr. 5 ^^^Sl 14 — 421 1 5 14 

The root of this species of clover is biennial; it 
penetrates to a great depth in the ground, and is in 
consequence little affected by the extremes of wet or 
dry weather. It requires good shelter, and a deep 
soil. The produce, when compared to that of others 
that are allied to it in habit, and place of growth, 
proves greatly superior. The following particulars, 
some of which refer to results stated in the next two 
pages, will make this manifest \ lbs. 

Trifolium pratenx "J Produces per acre. Grass 49005 

L Ditto, Hay 12251 

Bro^tJ^aved clover J Affords, ditto of nutritive matter 1914 

Medicago sativa. ") Produces per acre. Grass 70785 

Lucern. Frotp a soil t- Ditto, Hay 28314 

of the like nature J Affords of nutritive iratter 1659 



xliv APPENDIX. 



Hedysarum onobrychis. ") Produces per acre. Grass 

t Ditto, Hay 3539 

Saiiitfoin. J Affords of nutritive matter 314 

The weight oFnutritive matter afforded by the produce of the T. 
macrorhizum, exceeding that of the T- pratense, in proportion, 
nearly as 7 to 15 - - r 2297 

The proportional value of the grass of T. proiense 
to that of T, macrorhizum^ is 10 to 11. 

The weight of nutritive matter afforded by the T*. vmcrorhizum, 
exceeding that of the Medicago sativa, in proportion nearly as 
13 to 33 255? 

The proportional value of the grass is as 11 to 6. 

The weight of nutritive matter which is afforded by the produce of 
the T. macrorkizumf exceeding that of the Hedysamm onobrychis 
in proportion nearly as 5 to 67 3897 

The proportional value of the grass, like that of 
the T. pratense, is as 11 to 10. 

The produce of each of the above mentioned 
species, was taken from a similar soil, and in the same 
situation the conclusions must therefore be considered 
positive, with respect to such soils only. It is evident 
that more than twice the quantity of nutritive matter 
is afforded by the produce of one acre of the T. mai> 
crorhizunij than from the produce of an equal space 
covered by the T. pratense. Its short duration in the 
soil (for if sown early in the autumn, on a rich light 
soil, it is only an annual plant) renders it fit only for 
green-food or hay; this in some measure lessens its 
value, when compared with the T. pratense. It pos- 
sesses the essential property of affording abundance of 
good seed; and if the ground be kept clear of weeds, 
it sows itself, vegetates, and grows rapidly, without 
covering-in, or any operation whatever. For four 



APPENDIX. xlv 

years it has propagated itself in this manner, on the 
space of ground which it now occupies, and from which 
this statement of its comparative value is made. The 
produce of lucern in grass, comes nearer to this spe- 
cies in quantity, but is greatly deficient in nutritive 
matter, as much as 13 to 33. The long continuance 
of lucern in the soil is therefore the only merit which 
it possesses above the two last mentioned species; and 
when that is the object of the cultivator, it will of ne- 
cessity have the preference. 

The value of the grass of saintfoin is equal to 
that of the T. prateme; and proportionally less than 
that of the Trifolium macrorhizum, as 10 to 11. The 
quantity of grass is very small, and on soils of the na- 
ture above described, it is doubtless inferior. How- 
ever, from the superior value of the grass, on dry hilly 
situations or chalky soils, it may in such situations 
possibly be their superior in every respect. 
LIV. Medicago Sativa. Wither. B. 3. P. 643. 
Lucern. Nat. of Britain. 
At the time the seed is ripe, the produce from a rich 

clayey loam, is oz. or lbs. per acre 

Grass, 104 oz,. The produce per acre 1132560 — 70785 

80 dr. of grass weigh when dry 32 dr. 



dr.? 

jj. > 26544 6 — 7659 



rfu A f*i r*. <;/:« o o c \ 453024 — 28314 

The produce or the space, ditto 665. 2 2-5 J 

The weight lost by the produce of one acre in drying 42471 

61 dr. of gr-iss afford of nutritive matter 1.2 dr. ' 

The produce of the space, ditto 39 di 

LV. Hedysarum onebrychis. "Wither. 3. P. 628. 
Saintfoin. Nat. of Britain. 

At the time the seed is ripe, the produce from a rich 
clayey loam, is 

L^rass; 13 02. The produce per acre 141570 — 8848 2 



1.2 dr. 7 

JQJ2 P^30 1— 345 10 1 



xlyi APPENDIX. 

oz. or lbs. per acre 
8.0 dr. of gTass weigh when dry 32 dr. > 

The produce of the space, ditto 83 1-5 dr. 5 ^^^^^ — 3539 4 
The M eight lost by the produce of one acre in drying 5308 14 

64 dr. of grass afford of nutritive matter 2 2 dr. 
The produce of the space, ditto 

LVI, Hordeum pratense. Engl. Bot. 409. Host. G. 
A. 1. t. 33. Meadow barley-grass. Nat. of 
Britain. 

At the time of flowering, the produce from a 
brown loam, with manure, is 

Grass, 12 oz. The produce per acre 130680 — 8167 8 

80 dr. of grass weigh when dry 32 dr.") 

r.M 1 r.i J-..; /:* -. 1 C 52272 — 3267 

The produce of ihe space, ditto 67. 1 dr. 3 

The weight lost by the produce of one acre in drying 4900 8 

€4 dr. of grass afford of nutritive matter 3.3 dr."> 

The produce ofthe space, ditto 11.1 dr.5 ''^^^ — 478 9 

LVII. Poa compressa. Engl. Bot. 365. 

Flat-stalked meadow grass. Nat. of Britain. 

At the time of flowering, the produce from a gravelly 
soil, with manure, is 

Grass, 5 oz. The produce per acre 54450 — 3403 2 

80 dr. of grass weigh when dry 34 dr.") 

The produce of the space, ditto 34 dr.5 23141 4-1446 5 4 

The weight lost IjjMtlie produce of one acre in drying 1956 12 12 

64 dr. of grass afford of nutritive matter 5 di*.') 

„, , i^, ,.,, f. , C 4253 14—265 13 14 

The produce ofthe space, ditto 6. 1 -> 

/ . 

The specific characters of this species are much 
the same as those of the Poa fertilis, differing in the 
compressed figure of the straws, and creeping root 
only. If the produce was of magnitude, it would be 
one of the most valuable grasses; for it produces foliage 
early in the spring, and possesses strong nutritive 
powers. 



1 79122 —4945 2 10 



APPENDIX. xlvii 

LVIII. Poa aquaiica. Curt. Lond. Engl. Bot. 1315. 
Reed meadow grass. Nat. of Britain. 

At the time of flowering, the produce from a strong 

tenacious clay, is oz. or lbs. per acre 

Grass, 186 oz. The produce per acre 2025540 — 126596 4 

80 dr. of grass wei^h when dry 48 dr. ") 

Ti 1 f., v./ 1-73^ oc,i«r 1215324 —75957 12 

The produce of the space, ditto 1785.2 2-16 J 

The weight lost by the produce of one acre in drying 50638 8 

64 dr. of grass afford of nutritive matter 2.2 dr. 
The produce of the space, ditto 116. 1 dr. 

LIX. Aira aquatlca. Curt. Lond. Engl. Bot, \551, 
Water hair grass. Nat. of Britain. 

At the time of flowering, the produce from water, is 

Grass, 16 oz. The produce per acre 174240 — 10S90 

80 dr. of grass weigh when dry 24 dr. -^ __ 

the produce ofthe space, ditto 76.3 l-iej ^^^''^ — 3267 

The weight lost by the produce of one acre in drying 7623 

64 dr. of grass afford of nutritive matter 2. 1 dr.-^ 

The produce ofthe space, ditto 9 dr. j 6125 10 — 382 13 10 

LX. Bromus crisiaius, Triticum cristatum, H. G. 
A, 2. t. 24. Secale prostratum. Jacquin. Nt^t. 
of Germany. 

At the time of flowering, the produce from a clayey 
loam, is 

Grass, 13 oz. The produce per acre 141570 — 8848 

80 dr. of grass weigh when dry 32 dr.") ^ 

rr,u 1 c^r. J... oo 1 J \ 56628 — j5jy 4 

The produce ofthe space, ditto 83. 1 dr. J 

The weight lost by the produce of one acre in drying 5308 14 

64 dr. of grass afford of nutritive mjfcter 2-2 dr. "J o^e m n 

The produtt of the space, ditto 8.0 2-163 



xlviii APPENDIX. 

LXL Elymus Sibiricus. Hort. K. I. P. 1Y6. Cult. 
1758, by Mr. P. Millar. Siberian lyme grass* 
Nat. of Siberia. 
At the time of flowering, the produce from a sandy 
loam, with manure, is 

02. or lbs. pei icre 

Grass, 24 oz. The produce per acre 261360 — 16335 
80 dr. of grass weigh when dry 28 dr. > 

The produce of the space, ditto 134. 1 2-5 5 '^^^'^^ ^ "~ ^''^'^ ^ ^ 

The weight lost by the produce of one acre in drying 10617 12 

64 dr. of grass afford of nutritive matter 2-1 dr. ^ 

The produce ofthc space, ditto 13.2 dr. ^^^^^ '^ 511 7 

LXII. Aira caspitosa. Host. G. A. 2. t. 42. EngL 
Bot. 1557. Turfy hair grass. Nat. of Britain. 

At the time the seed is ripe, the produce from a 
strong tenacious clay, is 

Grass, 15 oz. The produce per acre 163350 6 — 10209 6 

80 dr. of grass weigh when dry 26 dr. ~) 

Tu , f-M v.. ,r,ei c f 53088 12 — 3318 12 

The produce of the space, ditto 1351-5 3 

The weight lost by the produce of one acre in drying 6891 5 4 

64 dr. of grass afford of nutritive matter 2 dr. ^ 

The produce of the space, ditto 7-2 dr. \ ^^^^ ^^ ~ ^^^ ^ ^^ 

LXIII. Hordeu?n murinwn. Curt. Lond. Engl. Bot. 
1971. Wall barley grass. Way Bennet. 
Nat. of Britain. 

At the time of flowering, the produce from a clayey 
loam, is 

Grass, 18 oz. The produce per acre 196020 — 12251 4 

80 dr. of grass weigh when dry 28 dr. 7 

The produce of the space, do 100.3 1-53 ^^607 0-4287 15 

The weight lost by the produce of one acre In drying 7963 5 

64 dr. of grass afford of nutritive matter 3 dr. ) 

The produce of the space, ditto 3.3 3-165 ^^'^^ *^ "* ^^^ "^ ^^ 



' APPENDIX. xhx 

LXIV. Avena flavescens» Curt. Lond. Engl. Bot 
952. Yellow oat-grass. ' Nat. of Britain. 
At the time of flowering, the produce from a clayey 

loam, IS oz or lbs. per acre 

Gr. ss, 12 oz. The produce per acre 130680 — 8167 8 
80 dr. of grass weigh when dry 28 dr."^ 

The produce ofthe space, ditto 67. 1 3 '^^^"^^ — 2858 10 

The weight lost by the produce of one acre in drying 5308 14 

64 dr. of grass afford of nutritive matter 33 dr. 7 

The produce of die space, ditto ll.ldr-S "^^^"^ — 478 9 

At the time the seed is ripe, the produce is 

Grass, 18 oz. The produce per acre 196020 — 12251 4 

80 dr. of grass weigh when dry 32 dr -v 

The produce ofthe space. dUto 115.0 4-,^ ^^^^^ 0- 4900 8 

The weight lost by the produce of one acre In drying 7J50 12 

64 dr. of gr.«?s afturd of nutritive matter 2. 1 dr. ") 

' 6S91 5— 430 11 



ir2. Idr.") 
10. I J 



The produce ofthe space, ditto 

The weiglit of nutritive matter which is lost if the crop be 
left till the seed be ripe, excfcdi g one-tenth part of its 
value 47 13 11 

The proportional value which the grass at the 
time the seed is ripe, bears to that at the time of flower- 
ing, is as 9 to 15. 

The produce of latter-math is 

Grass, 6 oz. The produce per ucre 65340 — 4083 12 

64 dr. of Grass afford of nutritive matter 1.' dr. !2r6 2 — 79 12 2 

The proportional value which the grass of the 
latter-math, bears to that at the time of flowering, is 
as 5 to 15j and to that at the time the seed is ripe, as 
5 to 9. 

This species is pretty generally cultivated in many 
parts of this kingdom; and it appears from the above 
details to be a valuable grass, though inferior to many 
others. 

g 



L APPENDIX. 

LXV, Bromus sterilis. Engl. Bot. 1030. Host. G. 
A. 1. t 16. Barren Brome grass. Nat. of 
Britain. 
At the time of flowering, tbe produce from a sandy 

soil IS 7. r Ih;. p. I acre. 

Grass, 44 f>z. 7 he produce per acre 479160 — 29947 8 

80 dr. of ura s weich w!ien dry 45 dr •) 

„,. ," ,.„ ,../ „o« . C 269527 8 — 16845 7 8 

1 lie produce of the sptxi, ditt ' 396 U. 3 

The weight lost Hy the produce of one acr(» in dr3ing 13102 8 

64df. ofg'i'ss /AT d of mitrUjve maUer Sd-.l 

The produc • of the space, ditto 55 dr. S ^^'^^^ ^~ ^^^^ ^^ ^ 

64 dr. of the flowers afford of nutritive matter 2.2 dr. 
The nutritive powers of the straws and leaves are, 
therefore, more than twice as great as those of the 
flowers. This species, being strictly annual, is of 
comparatively little value. The above particulars 
shew that it has very considerable nutritive powers, 
more than its name would imply, if taken at the time 
of flowering; but if left till the seed be ripe, it is like 
all other annuals comparatively of no value. 

LXVL Holais 7noUis, Curt. Lond. Wither. B. 2. P. 
1 34. Creeping soft grass. Nat. of Britain. 
At the time of flowering, the produce from a sandy 
soil, is 

Grass, 50 02. The produce per acre 544500 — 31031 4 

SO dr. of erass weieh when drv 32 dr. 1 

'TK 1 i-M A- J oo,. 1 r Jl''80O 0—13612 8 G 

The produce or the space, ditto 320 dr. J 

The weight lost by the produce of one acre in drying 20418 12 

64 dr. of grass aflord of nutritive tnatie- 4.2 dr,-j ^ 

The produce of the space, ditto 56. 1 dr.f ^^^^^ 2 — 2392 13 € 

At the time the seed is ripe, the produce is 

Grass, 31 oz. Tlie produce per acre 33?'590 — 21099 6 

$'0 dr. of gra.ss weig'l) when dry 32 dr. 7 

The produce of the space, do 198 1 3-5i *^^^^^ ^ '" ^*39 12 



APPENDIX. ^l 

oz. or lbs. ^er sere 
The v,eig-ht lost by the produce of one acre in drying 12659 10 

64 dr. of y rass afford of nutiitive niattei- 3.2 dr. > 

The produce of the spac?, ditto 27.0 2-53 



18461 15-- 1153 13 15 



The weiglu of nutritive matter which is lost by leaving the 
crap till the seed be ripp, beiog nearly one lia'f ol its 
value 1238 IS 3 

64 dr. of the roots kfFord of nutritive matter 5.2 dr. 

The proportional value which the grass at the 
time the seed is ripe, bears to that at the time of flower- 
ing, is as 1 4 to 1 8. 

The above details prove this grass to have merits 
which, if compared with those of other species, rank 
it with some of the best grasses. The small loss of 
weight which it sustains in drying might be expected 
from the nature of the substance of the grass; and the 
loss of weight at each period is equal. The grass 
affords the greatest quantity of nutritive matter when 
in flower, which makes it rank as one of those best 
adapted for hay. 

LXVII. Poa fertilis. Var. B. Host. G. A. The 
species. Fertile meadow grass. Variety 1. 
Nat. of Germany. 

At the time of flowering, the produce from a brown 
sandy loam, is 

Grass, 23 oz. The produce per acre 250470 — 15654 6 

80 dr. of gi'ass weigh wlien dry 34 dr."> 

Tlie produce of the space, ditto 156 2-53^°^^^^ — 6653 8 

The weiglit lost by the produce of one acre in drying 9000 14 

64 dr. of grass afford of nuti itive mutter 3 dr. "1 

The produce of the space, ditto 17.1 dr.3 ^^^^^ '^~ "^^^ ^^ ^^ 

At the time the seed is ripe, the produce is 

Grass, 22 v)z. The prcduee per acre 239580 — 14973 12 

80 dr. of grass weigh when dry 44 dr. 

The produce of the space, diltD 193.2 dr 



lr.7 

j^ I 131769 0— 82.35 C Q 



MI APPENDIX. 

oz. or Ihs. per acre 
The weig'lit lost by tlie produce of one acre in drying 6738 3 

64 dr. of errass aftord of nutritive matter 5 dr. ") 

-r. ». ^ e*u r.. o* o 1 C 18717 3 — 1169 13 5 

Ihe produce of the space, ditto 27. 2 dr. j 

The weight of nutritive matter which is lost by taking" the 
crop at the time of flowering, exceeding one third part 
of its v^lue is 436 1 3 

The proportional value which the grass at the 
time of flowering, bears to that at the time the seed is 
ripe, is as 12 to 20. 

The produce of latter-math is 

Grask, 7 oz. 'I'he product- per aci e 76230 — 4764 6 

64dr.ofgrass afford of nuriiiv.- matter, 12 di-. 1786 10 — 111 10 10 

The proportional value which the grass of the 
latter-math, bears to that at the time of flowering, is 
as 6 to 12; and to that at the time the seed is ripe, as 
6 to 20. 

LXVIII. Cynosurus eriicaformh, Beckmannia erucse- 
formis. Host. G. A. 3. t. 6. 
Linear-spiked dog*s-tail grass. Nat. of 
Germany. 

At the time the seed is ripe, the produce is 

Grass, 18 oz. The produce per ac e 196020 — 12251 4 

80 dr. of grass weigh when dry 36 dr. 



Thepn.duceofthespace, ditto 129. 2 2-5 i ^^^°^ -- 5513 1 
The weight lost by the produce of one acre in drying 6738 3 

64 cSr of grass afford of nutritive matter 31 dr. ' 



The prnducc- of the .space, ditto 14.2 2 4^^^^^ 2—622 2 2 

LXIX. Phkum nodosum, W. B. 2. P. 11 8. 

Bulbous stalked Cat's-tail grass, Nat. of Bri- 
tain. 

At the time of flowering, the produce from a clayey 
loam, is 
4Jrass, J8oz. The produce per acre 196020 — 12251 4 



APPENDIX. tin 

0?. or lbs. per acre 



80 dr. of cfrasa weiprh when dry 33 dr. , 

^ "^ 93109 8— 5819 5 8 



The produce of the space, ditto 1364 

The v/eight 1 st by the produce of one acre in drying 6431 14 8 

64 dr. of grass afford of nutritive matter 2.2 dr. > 

Ti J c.u J.* 11 -i A C76S7 0—478 9 

The produce of the spac , ditto 11.1 dr. 3 

This grass is inferior in many respects to the 
Phleum pratense. It is sparingly found in meadows. 
From the number of bulbs which grow out of the 
straws, a greater portion of nutritive matter might 
have been expected. This seems to prove, that these 
bulbs do not form so valuable a part of the plant as 
the joints, which are so conspicuous in the Phleicm 
pratense, the nutritive powers of which exceed those of 
the P, nodosum^ as 8 to 28. 
LXX. Phleum pratense. Wither. 2. P. 1 1 7. 

Meadow cat*s-tail grass. Nat. of Britain. 
At the time of flowering, the produce from a clayey 
loam, is 

Grass, 60 oz. The produce per jicre 653400 -- 40837 8 

80 dr. of errass weieh when dry 34 dr.-> 

^. , p,. ,. , .„„, f 277695 0—17355 15 

The produce of the space, ditto 408 dr.3 

The weight lost by the produce of one acre in drying 23481 9 

64 dr. of grass afford of nutritive matter 2-2 «lr, 



The produce of the space, ditto 37.2 dr. 3 ^^^^^ '' — ^^^^ 

The weight of nutritive matter which is lost by leaving the 

ci'op till the seed be ripe, excee<Ung one half of its value 2073 11 

At the time the seed is ripe, the produce is 

Grass, 60 oz. The produce per acre 653400 — 40837 8 

dr.^ „ 
The produce of the space, ditto 456 dr. 5 ^ 

The weight lost by the p^ oduce of one acre in drying 21439 11 

64 dr. of grass afford of nutritive matter 5.3 dr. > 
The produce of the space, ditto 86.1 dr. 5 ^^'^^^ 14 — 3668 15 14 

The latter-math produce is 

Grass, 14 02. "I he pr^ duce pci acre 152460 — 9528 12 

64dr.ofgrRss afford of nutritive matter 2 dr. 4764 6— 297 12 6 



80 dr. of grass weigh when dry 38 dr. 

' 310365 — 19397 13 



iiv APPENDIX. 

64 dr. of the straws afford of nutritive matter 7 dr» 
The nutritive powers of the straws simply, therefore, 
exceed those of the leaves, in proportion as 28 to 8; 
and the grass at the time of flowering, to that at the 
time the seed is ripe, as 10 to 23; and the latter-math, 
to the grass of the flowering crop as 8 to 10. 

The comparative merits of this grass will appear, 
from the above particulars, to be very great; to which 
may be added the abundance of fine foliage that it 
produces early in the spring. In this respect it is 
inferior to the Poafertil'ts, and Poa ayiguestifolia only. 
The value of the straws at the time the seed is ripe, 
exceeds that of the grass at the time of flowering, as 
28 to 10; a circumstance which increases its value 
above many others ; for, by this property, its valuable 
early foliage may be cropped, to an advanced period of 
the season without injury to the crop of hay, which, in 
other grasses which send forth their flowering straws 
early in the season would cause a loss of nearly one 
half of the value of the crop, as is clearly proved by 
former examples ; and this property of the straws, 
makes the plant peculiarly valuable for the purpose of 
hay. 

LXXI. Phleu?n pratense. Var. minor. Wither. B. 
2. 118. Var. 1. Meadow cat*s-tail grass. 
Var. Smaller. Nat, of Britain. 

At the time of ripening the seed, the produce from a 

clayey loam, is oz. or Ibs. per acre 

(ii-Hss, 40 i.z. The produce per £cre 435600 — 27225 

yO dr. of erass ueicrh when dry ^A <lr 7 .- , 

, ^-^i vJ oTo . k 185130 0-11570 10 

J be produce o\ tlie space, ditlo- 272 ur. J 



APPENDIX. Lv 

02 or lbs per acre 

Tlie weight lost by the produce of one acre in drying 15654 6 

64 dr. of m-a&s afford of nutritive matter 2.3 dr. 7 .. .^ ,„ -, 

n,.U . r.U v.. err, A < 18717 3— 1169 13 3 

The fivo'.iice 01 the space, ditto 2/2 dr. J 

The latter-math produce is 

Grass, 14 oz. The produce per acre 152460 0—9528 12 

64 d) . 'if grass .iffurd of nutritive matter 1 2. dr. 3573 4 — 223 5 4 

LXXII. Elymus arevarius. Engl. Bot. 1672. 

Upright sea lyme grass. Nat. of Britain. 

At the time the seed is ripe, the produce from a 
clayey loam, is 

Grass, 64 oz. The produce per acre 696960 — 43560 Q 

80 dr. of grass wtigli when dry 45 dr. 

The produce of ihe space, ditto 576 dr. 

The weight lost by the produce of one acre in drying 18957 8 

64 dr. of grass aS'ord of nutritive matters dr. 

The produce of tiie space, ditto 80 dr. 

LXXIII. Elymus geniculatus. Pendulous lyme grass. 
, Engl. Bot. 1586. Pendulous sea lyme 
grass. Nat. of England. 

At the time of flowering, the produce from a sandy 
soil, is 

Gr-os, 30 oz. The produce per acre 32670O ~ 20418 12 

80 dr. of grass weigh wlien dry 32 dr. ~) 

TK 1 F.u V,. too 1 C 13068O 0— 8167 8 

i. he produce of the space, ditto 192 di. j 

The weight lost by ihe produce of one acre in drying 12251 4 

64 dr. of grass afford oi nutritive matter 3.1 dr. 

* 16590 3 — • 1036 14 3 



^Ir 392040 0—24502 8 



54450 — 3403 2 



:\ 



T!ie p-rokic-- of the spAce, ditto 24.1 1-2 dr. 

LXXIV, Bromus inermis. Host. G. A. 1. t. 9. 

Awnless brome grass. Nat. of Germany. 
Introduced by Mr. Hunneman in 1794. 
At the time the seed is ripe, the produce from a 
black sandy soil, is 

Grasb, 18oz. The produce per acre 196020 — 12:51 4 0, 

30 dr. of grass weigh when dry 35 dr. ) 

The prodmee of fee 8i.ace, jJattn i'?6 dr. S ^^'^^^'' ^^ ""•'^'^'^^ ^ ^'' 



ivi APPENDIX. 

07.. or lbs. per •I'rc. 
The weifjlit lost by the produce of one acre in drying 6891 5 4 

64 dr. of grass afford of nutritive matter 4. 1 dr. 1 

The produce of the space, ditto 19.0 3-5 j" 13016 15 — 813 8 15 

The produce of latter-math is 

Grass, 13 oz. The produce per acie 141570 — - 8848 2 

64 dr. of grass afford of nutritive matter 1. 1 dr. 2765 — 172 13 

LXXV. Agrostis 'vulgaris. Wither. Bot. 2, 132. 
Hud. A. capilaris, Dr. Smith, A. arenaria. 
Fine bent grass. Nat. of Britain. 

At the time the seed is ripe, the produce from a 
sandy soil, is 

Grass, 14 uz. The produce per acre 152460 — 9528 12 

80 dr. of grass weigh wiien dry 40 di- 

Tlje produce of the sjiace, ditto 

The weight lost by the produce of one acre in drying 4764 6 

64 dr. of grass afford ot nutritive matter 1.2 3-16 dr. ^ 

The produce of the spi^ce, diito 5.1 1-16 S ^°^^ 15— 2jI 3 15 

This is one of the most common of the bents, 
likewise the earliest ; in these respects it is superior 
to all others of the same family, but inferior to several 
of them in produce, and the quantity of nutritive mat- 
ter it affords. As the species of this family are 
generally rejected by the cultivator on account of the 
lateness of their flowering ; and this circumstance, as 
has already been observed, does not always imply a 
proportional lateness of foliage, their comparative 
merits in this respect may be better seen, by bringing 
them into one view, as to the value of their early 
foliage. 



40 di- 7 
, , , \ 76230 — 4764 6 
11^ ur. J 



APPENDIX. i,vu 

The apparent difference of time. Their nutritive power*. 

Agrostis vulgaris Middle of April 1.2 3-4 

palustris One week later 2.3 

stolonifera Two, ditto 3.2 

canina Ditto, ditto 1.3 

stricta Ditto, ditto 1.2 

nivea Three weeks, ditto 2 

Uttoralis Ditto, ditto 3 

repens Ditto, ditto 3 

mexicana Ditto, ditto 2 

fascicularis Ditto, ditto 2 

LXXVI. Agrostis palustris. Wither. Bot. 2, P. 129* 

Var. 2, alba. Engl. Bot. 1189. A. alba. 
Marsh bent grass. 

At the time of flowering, the produce from a bog 
earth, is 

oz. or lbs. per acre 
Grass, 15 oz. The produce per acre 163350 6 ~ 10209 6 

80 dr. of grass weigh v,'heo dry 36 dr.'j 

Thepvoduceofthe space, ditto 180 dr. V^^^ 8 — 4594 3 8 

The welg' it tost by the produce of one acre in drying 5615 2 8 

64 dr. of grass afford of nutritive matter 2. 3 dr."> 

The pro.'uc: of the space, ditto 10.1 1-43 ^°^^ *^"" ^^^ ^° ^^ 

At the time the seed is ripe, the produce is 

Grass, 20 oz. The produce per acre 217800 — 13612 8 

80 dr. of grass weigh when dry 32 dr. f 

A e^u A-.l 1O0J ^87120 0—5445 

The produce of the space, ditto 128 dr. > 

The weight lost by the produce of one acre in drying 8167 8 

64 dr. of grass afford of nutritive matter 2.3 dr. 7 
The produce of the space, ditto 13.3 dr. J 

The weight of nutritive matter which is lost by taking the ^ 
crop at the time of flowering, being one fourth part of its 

value 146 ,3 If* 

The proportional value of grass, in each crop is equal. 

h 



Lviw APPENDIX, 

LXXVII. Panicufn dactykn. Engl. Bot. S50. Host. 
G. A. 2, t. 18. Creeping Panic grass, 
Nat. of Britain. 

At the time of flowering, the produce from a sandy 
loam, with manure is 

oz or lbs per acre 
Grass, 46 oz. The produce per acre 500940 0—31308 12 

80 dr. of grass weigh when dry 36 dr.") 

The produce of the space, ditto 331.0 4-53 2254.23 — 1408815 

The weight lost by the produce of one acre in drying 17219 13 

61 dr. of grass afford of nutritive matter 2. dr. 5 

The produce of the space, ditto 23. dr. 5 '^^^^ ^ - ^'^^^^ ^ ° 

LXXVIII. Agrostis siolonifera. Engl. Bot. 1532. 

Wither. Bot. 2, 181. (Fiorin, Dr. Rich- 
ardson.) 
Creeping bent. Nat. of Britain. 

At the time of flowering, the produce from a bog 
soil, is 

Cirass, 26oz. The produce per acre 283140 0—17696 4 

80 dr. of grass weigh when dry 35 dr. "} 

TK r f.i r« ico^ t 127413 — 7963 5 

The produce of the space, ditto 182 dr. j 

The weig. lost by the produce of one acre in drying 9732 15 

64 dr. of grass .afford of nut- itive matter 3.2 dr. 



-ri 5 r.K j-.f no 9 . v 15484 3 — 967 12 3 

The produce of the spact ditto 22.3 -tr. ) 

At the time the seed is ripe, the produce is 

Grr,ss, 28 oz. The produce per acre 304920 — 19057 8 

f;0 dr. of grass weigh when dry 36 dr.") 

a-u A e.u A-,/ oni o <5 « f 137214 — 8575 14 

The produce of the space, ditto 201.2 2-5 J 

Tlie -weight lost by the produce of one acre in drying 10481 10 

64 dr. of grass afford of nutritive matter 3.2 dr.-j 

The produce ofthe space, ditto 24. 2 dr. 5 ^^^'^^ 0—1042 3 5 

Theweiglit of nutritive matter whichis lost by taking the crop 

at the time of flowering, being nearly one fourteenth of its 

value --.,-,. . , . 7'l! T 2 



APPENDIX. us 

LXXIX. Agrostis stolonifera. Var. angustifolia. 
Creeping bent with narrow leaves. 
Nat. of Britain. 
At the time the seed is ripe, the produce from ar 
bog soil, is 

oz. or lbs. per acre 

Grass, 24 oz. The produce per acre 261360 — 16335 

80dr.ofj,.assw^ighwhen.lry 36 clr ^ 117612 0-7350 12 

The produce ot ihe space, ditto / 172 3 1-5 j 

The weight lost by the produce oio. e »C!'t in dryhig 8984 4 

64 I ( . of grass afford ornutritive matter 3. <lr. > 

rp, (.,, ,.,* io I ('2251 4 — 765 11 4 

Th- prouucf. of the space, ditto 18 a 3 

The weight of nutritive matter afforded by the pro- 
duce of one acre of the Agrostis stolonifera, 
exceeding that of the variety in proportion, is 6 
to 8 - - - - 276 8 1 

The above details will assist the farmer in deci- 
ding on the comparative value of this grass From a 
careful examination it will doubtless appear to possess 
merits well worthy of attention, though perhaps not 
so great as has been supposed, if the natural place of 
it« growth and habits be impartially taken into the ac- 
count. From the couchant nature of this grass, it is 
denominated couch-grass, by practical men, and from 
the length of time that it retains the vital power, after- 
being taken out of the soil, is called squitch, quick, full 
of life, &c. 

LXXX. Agrostis canina, Engl. Bot. 1 856. 
Brown bent. Nat. of Britain. 

At the time of flowering, the produce from a brown 
sandy loam, is 

Grass, 9 oz. The produce per acre 98010 — 6125 10 



LX APPENDIX. 

oz. or lbs. per acre. 

80 dr. of grass weigh when dry 34 dr. 1 

The produce of the space, ditto 63 1-5 > ^^^^^ ° - ^^^S 5 

The weight tost by the produce of one acre in drying 3437 5 

64 dr. of grass afford of nutritive matter 2.2 dr ") 

Tbep-oduce of the space, ditto 5 211-2 3 3828 8 — 239 4 8 

LXXXI. Agrostis canina. Var. muticas. 

Awnless brown bent. Nat. of Britain. 
At the time the seed is ripe, the produce from a 
sandy soil, is 

Grjiss, 21 oz. 1 he prodxice per acre 228690 — 14293 2 
80 dr. of grass weigh when dry 24 dr. ^ 

The produce ofthe space, ditto 100.3 1-5 5 ^^^^'^ 0—4287 15 

The weight lost by the produce of one acre in drying 1C005 3 

64 dr. of grass afford of nutnlive matter 1.3 dr.'J 

The produce oft he sp ce, rlittu 9,0 3-4 5^"^^^"''^^ ^^ ^ 

The weight of nutritive matter which the produce of 
one acre of the awnless variety, exceeds that of 
the last mentioned species - 5 8 11 

LXXXII. Agrostis stricta> Curt. A. rubra. 
Upright bent grass. Nat. of Britain. 
At the time the seed is ripe, the produce from a 
bog soil, is 

Grass, il oz. The produce per acre 119790 — 7486 14 

80 dr. of grass weigh when dry 29 dr. 7 

The produce of tbe space, do 63 4-5 dr- 5 ^^^^^ ^^"' 2713 15 

The weight lost by the produce of one acre in drying 4772 15 

64 dr. of grass afford of nutritive matter 1.2 dr.) 

The p ■ .luce of the spic , ditto 4.0 5-10 \ ^807 9 — 175 7 9 

LXXXIII. Agrostis nivera. 

Snowey bent grass. Nat. of Britain. 
At the time the seed is ripe, the produce from a 
sandy soil, is 

Grass, 7 oz. The produce per acre 76230 — 4764 6 



80 dr. ofgra<;s weigh when dry 22 dv.-y 



\PPENDIX. LXi 

oz. 0? lbs. per acre 

20963 4 — 1310 3 



The produce of tlie spacf?, dtj. 303 1-5 Jr.^ 

The weight lost by tlie produce ot' one sere in dryhig 3454 3 

64 dr. of g'lass aflbrd of nutritive matter 2dr."S 

Thr nv'xlucr of tl>e space, ditto 3 1-2 dr. S 238;3— 148 14 3 

LXXXIV. Agrosiis fascicidaris. Huds. Var. 
canina. Curt. Tufted leaved bent. 
Nat. of Britain. 

At the time of flowering, the produce from a light 
sandy soil, is 

Gr.s., 4 z. the produce per acre AoS&O — 2722 8 
30 dr. of grass weigh when diy 20 '^'i","> 

The ,>roduceofthesp.ce, ditto ISdr^ ^^^^^ ^'^^^ ^0 

The Weight losthy tlie produce of one acn in drying 2041 14 

64 dr. of grass afford of nutritive matter 2 dr. 7 

1361 4—85 14 



dr. 7 
dr. 3 



rh n reduce of the snace, ditto 2 

LXXXV. Festuca pinnata. Bromus pinnatus. 

Engl. Bot. 73". 

Spiked fescue. Nat. of Britain. 
At the time the seed is ripe, the produce from a 
light sandy soil, with manure, is 

Grass. 50 02.. 1 he pro:,uce per sere 226700 — 20418 12 

80 dr of grass weigh when dry 32 dr. ) 

^, , P., r». 100 1 C 130680 0—8167 8 

The produce of the space, ditto 192 dr. 3 

The weight I'st by the produce of one acre in drying 12251 4 C 

64 dr. f grass afford of nutritive matter 1 1 dr. ) 

mu ^ r.i T... ni o.^ C 6380 13 — 398 12 13 

Tht • d'lCf of the sp-,c , ditto 912-4 3 

LXXXVI. Panicum viride. Curt. Lond. EngL 
Bot. 875. Green panic grass. Nat. of 
Britain. 
At the time the seed is ripe, the produce from a 

light sandy soil, is 

Grass, 8 oz. The produce per acre 87120 — 5445 



txii APPENDIX. 

C2. 01* lbs per acre 
80 dr. of grass v'elgh when dry 32 dr. 7 

The produce of the spsce, ditto 511-5 3 ^'^^'^^ — 2178 

The weight lost by the produce of one acre in dryir.g 3267 Q 

€4 or of grass affnrd of nutritive matter 1.2 dr. ^ 

rr, 1 f.K v., "• ^ 2'=41 14—127 9 14 

Tit' pr'Hlucc or th'~ . ppc?, di'ito o t. ) 

LXXXVIL Panicumsanqu'male. Curt. Lond. Engl. 
Bot. 849. Blood coloured panic grass. 
Nat. of Britain. 

At the time the seed is ripe, the produce from a 
sandy soil, is 

Grass, 10 wz The produce per acre 108900 — 6P"6 4 9 

64 dr. of sras.s fF.rd of nutritive matter 1 2-16 1914 4— 19'")4 

This and the preceding species are strictly annu- 
al, and from the results of this trial, their nutritive 
powers appear to be very inconsiderable. The seed 
of this species, Mr. Schreber describes (in Beschrei- 
bung der Graser) as the manna grass. In Poland, 
Lithuania, &c. it is collected in great abundance, when 
after being thoroughly separated from the husks, it is 
fit for use. When boiled with milk, or wine, it forms 
an extremely palatable food, and is most commonly 
made use of whole, in manner of sago, to which it is in 
general preferred. 

LXXXVIII. Agrostis lobata. Curtis, lobata et are- 
naria. Lobed bent grass. 

At the time of flowering, the produce from a sandy 
soil, is 

Grass, 10 oz. The produce per acre 108900 — 6806 4 

aOdr.ofgrasswe-.ghwhendry 40dr.^ ^^^.^^ 0-3403 2 
The produce of the space, ditto 80 dr. 5 

TliC weight lost by the produce of one ;irre in dryinij 3403 2 



■ APPEND-IX. Lxiu 

oz. or lbs. per acre 
64 dr. ofgrassaflordornutrltive matter 3dr.-j 

Th- produce oi' ihe sp'.ce, ditto 7.2 dr.j ^^°'^ 11—319 11 

LXXXIX. Agrostls repens. Wither. Bot, A. nigra. 
Creeping rooted bent, black bent. Nat. 
of Britain. 

At the time of flowering, the produce from a clayey 
loam, is 

Gras-, 9 oz. Ths produce per acre 98010 — 6125 10 

80 dr. of grrtss weigh wlu-n dry 3.5 dr.") 

Tl)u produce nfthe space, ditto 63di-3 42879 6—2679 15 6 

The weight l^-st by the produce of one acre in drying 3445 10 10 

64 dr. of grass afford of nuti-itl ve matter 3 dr. ^ 

Theprcduceofihe spuce, ditto 6.3 dr. 5 ^"'^^^ ^. "" ^^'' ^ 3 

XC. Agrostis 77iexicana. Hort. Kew. I. P. i5o„ 
Mexican bent grass. Nat of S. America.— 
Introduced 178'.i, by M. G. Alexander; 
At the time of flowering, the produce from a 

black sandy soil, is 

Grass, 28 oz. Ihe produce per acre 304920 — 19057 8 

80 dr. of grass weigh when dry 28 dr.-^ i 

The produce ofthe space, ditto 156,3 1-55 ^"^^^^'^ 0—6670 2 

The weightiest by the produce of one acre in drying 12387 6 0. 

64 dr of gratis affurd of nutritive matter 2. dr. 1 

The p. odace of the sp. ce, ditto 14 d;' J ^^^^ ^^ "" ^^^ ^ ^^ 

XCI. Stipa pennata, Engl. Bot. 1356. Long- 
awned feather grass. Nat. of Britain. 

At the time of flowering the produce from a heath 
soil, is 

Grass, 14 oz. The produce per acre 152460 — 9523 12 € 

80dr. of grass weigh when dry 29dr.7 ^ ^^.-„_.^.. • 

T he produce of the space, ditto 81 1-5 dr J 

The weight lost by the produce of one acre in dryinrj 6074 9 A- 



txiv APPENDIX. 

cz. or ibs. per acre 

64 dr. of rrassafT'ird of nutiiUve maUer 2.3 dr.-j -^., ^ >^„ ^ -. 
„ (. 6551 — 409 7 

Tlip produce ( f tl»e spjiCf, uitU) ' 9 2 1-2 3 

XCII. Triticum repens, Engl. Bot. 909. 

Creeping rooted wheat grass. Nat. of 

Britain. 
At the time of flowering, the produce from a light 
clayey loam, is 

Gi-.iSE, 18 oz. Tlie produce per «cre 196020 0-- 12251 4 

SO Jr. of grass weigh when dry 32 dr. | 78408 — 4900 8 

The produce of the space ditto 115 1-5 j 

The weight lost by the produce of one acre in drying 7350 12 

64 dr. of tjrass afford of nutritive matter 2 dr. ^ gjgs iQ 382 13 10 

The proiluce "if the space ditto 9 dr. > 

64 dr. of the roots, afford of nutritive matter 5.3 dr. 
The proportional value of the roots, is therefore to 
that of the grass, as 23 to 8. 
XCIII. Alopecurus agresiis. Engl. Bot. 848. 

A. myosuroides. Slender fox-tail grass. — 
Nat of Britain. Curt. Lond. 
At the time of flowering the produce from a 
light sandy loam is 

iiiass, li; oz. The iuoduce per acre 130680 — 8167 8 

80 dr. of grass weigh v.hen dry 31 dr^ ^^^33 8__3i64 14 g 

1 he p oduce of tlie space ditto 74 1 3-5 dr, > 

<S4 di. of grass afford of .'utritive matter 1.3 dr. ? . „. 

^ , , > o5/o 4 — 223 5 4 
The roduce 01 the si^ce aitto 5.1 dr, > 

XCIV. Bromus aspcr. Engl. Bot. 1172. Curt. 

Lond. Bromus hirsutus. Huds. Bromus 
ramosus. B. sylvaticus, volger. B. altissi- 
mus. Hairy stalked brome grass. Nat. of 
Britain. 
At the time of flowering, the produce from a lighi. 

sandy soil, is 

Grass, 20 oz. The produce per acre 217800 — • 13612 8 



APPENDIX. Lxv 

80 dr. of grass weigh when dry 24 dr -> 

The produce of the space, ditto. PSdr.V^^^^ — 4083 12 

The weiglit iost hy tl)e produce of one acre in <lrying 9528 12 

64 dr. of grass afford of nutritive matter 2 dr. ") 

Thr- product' o''i he space, ditto lOd.l^^^'^ 4 — 425 6 4 

XCV- Phalaris canariensis, Engl. Bot. 1310. 
Common canary grass. Nat. of Britain. 
At the time of flowering, the produce from a clay» 
ey loam, is 

Grass, 80 oz. The produce per acre 871200 — 54450 

80 dr. of grass weigh when dry 26 dr.-* 

The produce oftiiespnce, ditto 416 dr.f ^^^^''^ 8—17697 9 8 

The produce in weight lost hy drying ... 36752 6 6 

64 dr. of grass afford of nutritive matter 1.2 dr. 1 

The p.od.iceofthespacf, ditto 30drj20418 12-1876 2 12 

XCVI. Melica ccerulea. Curt. Lond. Engl, Bot. 750 
Purple melic grass. Nat. of Britain. 
At the time of flowering, the produce from a light 
sandy soil, is 

Grass, 11 oz. The produce per acre 

80 dr. of grass weigh when dry 30 dr.-j 

The produce of the space, ditto 66dr.3 

The weight lost by the produce of one acre in drying 

64 dr. of grass afford of nutritive matter 1.2 dr. 7 

The produce of ihe space, ditto 4.0 2-4 3 ^^^^ 8 — 172 4 8 

XCVII. Dactylis cynosuroides.\Ami,^\,hsculyV. 17. 

American cock's foot grass. Nat. of N. 

America. 
At the time of flowering, the produce from a clayey 
loam, is 

Grass, 102 oz. The produce per ^cre 111780 — 69423 1 

80 dr. of grass weigh when dry ^^ ^^'\&f>(AlS9 ^ ^\6S^ 4 
The produce of the space, ditto 979 1-5 dr. J 

The weight lost by the produce of one acre in drying 27769 8 

64dr.ofgrassafrordofnutritivematterl.3dr7 ^^^^ ^ _^^^^ ^ ^ 
The produce of the space, ditto 44.2 2-4-» 



oz. 


or 


lbs. per acre 


119790 


0- 


-7486 


14 





44921 


4- 


- 2807 


9 


4 


Irying 




4679 


4 


2 



1^X\ I 



APPENlSlX. 



Cfthe Time in which different Grasses pro- 
dnce Fl we)s cnul Seeds. 

To decide positively the exact period or season, 
■when a grass always comes into flower, and perfects 
its seed, will be found impracticable; for a variety of 
circumstances interfere. Each species seems to pos- 
sess a peculiar life in which various periods may be 
distinctly marked, according to the varieties of its age, 
of the seasons, soils, exposures, and mode of cukure. 

1 he following Table, which shews the time of 
flowering, and the time of ripening the seed of those 
grasses growing at Woburn, which are mentioned in 
the Experiments, must, therefc e, only be considered 
as serving for a test of comparison, for the different 
grasses, growing under the same circumstances. 



Names. 


Time of 


Time of ripening 


flowering. 


the 


eed. 


Anthonanthum odoratum 


April 29 


June 


21 


Ilolcus odoratus 


April 29 


June 


2i 


Cynosurus caruleus 


April 30 


June 


SO 


Alopecurus pratensis 


May 20 


June 


34 


Alopecurus alpinus 


May 20 


June 


24 


Foa alpina 


M»y 30 


June 


30 


Poa pratensis 


M^y 30 


July 


14 


JPoa caerulea 


May 30 


July 


14 


Avena pubesceiis 


June 13 


July 


8 


Festucrf Hordiformis 


June 13 


July 


10 


Poa trivialis 


June 13 


July 


10 


Festuca glauca 


June 13 


July 


10 


Festaca gUbra 


June 16 


July 


10 


Festuca rubra 


June 20 


July 


10 


Festuc:i ovina 


June 24 


July 


10 


Briz) media 


June 24 


July 


10 


Dactylis gloinerata 


June 24 


July 


14 


Bromus teetotum 


June 24 


July 


15 


Festuca cambrica 


June 28 


July 


19 


Bromus diandrus 


June 28 


July 


16 


Po^ angustil'olia 


June 28 


July 


16 


Avena elatior 


June 2S 


July 


IS 


Poa elatior 


June 28 


July 


19 


Festuca duriascula 


July 1 


July 


20 


Milium effusuDi 


July 1 


July 


30 


Festuca pratensis 


July 1 


July 


20 


I/Olium perenne 


July 1 


July 


20 



APPENDIX. 



LXVll 



.__ — y ■ . 


Time 


of 1 


Tine of ripening 


Names. 


flowering. 


the See'l 


Cynosurus crist itus 


July 


6 


July 28 


Avena pr^teiisis 


July 


6 


July 20 


Bromus multiflorus 


July 


6 


July 2S 


Festuca loli-icea 


July 


I 


July 28 


Poa cristata 


July 


4 


July !S 


Festuca myurua 


July 


6 


July 28 


Airii flexuosa 


July 


6 


July 28 


Hoideuni bulbosam 


July 


10 


July 28 


Festuca calamaria 


July 


10 


July 23 


Bromus littoreus 


July 


12 


Aug. 6 


Festuca elatior 


July 


12 


Aug. 6 


Naidus stricta 


July 


12 


Aug. 6 


Tritjeum, (specie* oQ 


July 


12 


Aug. lO 


Festuca Fluitans 


July 


14 


Aug. 12 


Festuca dumetorum 


July 


14 


July 20 


Holcus lanatus 


July 


14 


July 26 


Foa fertilis 


J-ly 


14 


July 23 


Arundo colorata 


July 


16 


July 28 


Poa (species of) 


July 


16 


July 30 


Cynosurus erucatformis 


July 


16 


July 30 


Phleum nodosum 


July 


16 


July 30 


Phleum pratense 


July 


16 


Jnly 30 


Flymus arenarius 


Jaly 


18 


July 30 


Klymus geniculatus 


July 


18 


July 30 


TrifoHum pratense 


July 


18 


July 30 


Trifolium macrorhizum 


July 


13 


July 30 


Sanguisorba canadensis 


July 


IS 


July 30 


Bunias orientalis 


July 


18 


July 30 


Medieago sativa 


July 


18 


Aug. 6 


Jledysarum onobrychii 


July 


18 


Aug. a 


Hordeum pratense 


July 


20 


Aug. 8 


Poa compre&aa 


July 


20 


Aug. 8 


Poa aquatica 


July 


20 


Aug. 9 


Bromus cristatus 


July 


24 


Aug. 10 


Klymus sibircus 


July 


24 


Aug. 10 


Aira cafspitos^i 


July 


24 


Aug. 10 


Avena flavesceng 


July 


24 


Aug. 15 


Bromus sterilis 


July 


24 


Aug JO 


Holcus mollis 


July 


24 


Aug. JO 


Bromus inermis 


July 


24 


Aug. 20 


Agrostis vulgaris 


July 


24 


Aug. 20 


Agrostis p.lustris 


July 


28 


Aug. 88 


Panicum dactylon 


July 


28 


Aug. 28 


Agrostis stolonifera 


July 


23 


Ang. 2J 


Agrostis stolonifera (var.) 


July 


23 


Aug. S3 


Agrostis canina 


July 


28 


Aug. 2S 


Agrostis stricta 


July 


28 


Aug. 39 


Festuca pennata 


July 


38 


Aug, 30 


Panicum viride 


Aug. 


3 


Aug. 1* 


Panicum sanguinale 


Aug. 


6 


Aug. 20 


Agrostis lobata 


Aug. 


6 


Aug. 20 


Agrostis repens 


Aug. 


8 


Aug. as 


Agrostis fascicularis 


Aug. 


10 


Aug. 30 


Agrostis nivea 


Aug. 


10 


Aug. 30 


Triticura repens 


Aug. 


10 


Aug. 30 


Alopecurus agrestic 


Aug. 


10 


Sept. 8 


Bromus asper 


Aug. 


10 


Sept. 10 


Agrostis mexicana 


Aug 


15 


Sept. 25 



LXVIII 


APPENDIX. 




Names. 


■" Time of 
Sewering- 


Time of ripening 
the Seed. 


Stipa pennata 
Melica csmlea 
rhalaris caiianiensis 
Dactylis cynoturoides* 


Aug. IS 
Aug. 20 
Aug. 30 
Aug, 30 


Sept. 35 
Sept. 30 
Sept. 30 
Oct. 20 



Of the different Soils referred to in the 
Appeiidicc, 

In books on agriculture and gardening much un- 
certainty and confusion arises from the want of regu- 
lar definitions of the various soils, to distinquish them 
specifically by the names generally used: thus the term 
bog-earth, is almost constantly confounded with peat- 
moss, and heath-soil; also the term ' light loam,* 
' heavy soil,* &c. are given without distinguishing whe- 
ther that be ' light* from sand, or this * heavy* from 
clay. In minute experiments, it is doubtless of con- 
sequence to be as explicit as possible in those parti- 
culars. The following short descriptions of such 
soils as are mentioned in the details of the experiment 
are here given for the above purpose, 

1st. By ' loam* is meant any of the earths com- 
bined with decayed animal, or vegetable matter. 

2nd. ' Clayey-loam* when the greatest propor- 
tion is clay. 

3rd. * Sandy- loam* when the greatest proportion 
is sand. 



* In the •xpcriments made en the quantity of nutritive matter in the gruan, 
cut at the time the seed was ripe, the seeds were always separated: and the calcu- 
lations for autritire nutter, as i« erident from the details, made for grass aad 
set hzf. 



APPENDIX. ixjx 

4th. ' Brown-loam* when the greatest proper-^ 
tion consists of decayed vegetable matter. 

5th. * Rich black loam* when sand, clay, ani- 
mal and vegetable matters are combined in unequal 
proportions, the clay greatly divided, being in the least 
proportion, and the sand and vegetable matter in the 
greatest. 

The Terms ' light sandy soil,* ' light brown 
loam,* &c. are varieties of the above, as expressed. 



Lxx APPENDIX. 

Oh nerval ions on the chemical Composition of 
the nntrliive matter afforded by (he i^ras- 
ses in their difftrenl Suites. By the Edi- 
tr. 

I have made experiments on most of the soluble 
products supposed to contain the nutritive matter of 
the grasses, obtained by Mr. Sinclair; and 1 have an- 
alysed a few of them. Minute details on this subject 
would be little interesting to the agriculturist, and 
would occupy a considerable space; I shall therefore 
content myself with mentioning some particular facts, 
and some general conclusions, which may tend to elu- 
cidate the inquiry respecting the fitness of ihe different 
grasses for permanent pasture, or for alternation as 
green crops with grain. 

The only substances which I have detected in the 
soluble matters procured from the grasses, are mucil- 
age, sugar, bitter extract, a substance analogous to 
albumen, and different saline matters. Some of the 
products from the after-math crops gave feeble indica- 
tions of the tanning principle. 

The order in which these are nutritive has been 
mentioned in the First Lecture, the albumen, sugar, 
and mucilage, probably when cattle feed on grass or 
hay, are for the most parr retained in the body of the 
animal; and the bitter principle, extract, saline mat- 
ter, and tannin, when any exist, probably for the most 
part are voided in the excrement, with the woody 
fibre. The extractive matter obtained by boiling the 
fresh dung of cows, is extremely similar in chemical 



APl'ENDIX. Lxxi 

characters to that existing in the soluble products from 
the grasses. And some extract, obtained by Mr. Sin- 
clair, from the dung of sheep and of deer, which had 
been feeding upon the Lolium perenne, Dactylis glom- 
erata, and Trifolium repens, had qualities so anala- 
gous to those of the extractive matters obtained from 
the leaves of the grasses, that they might be mistaken 
for each other. The extract of the dung, after being 
kept for some weeks, had still the odour of hay. Sus- 
pecting that some undigested grass might have remain- 
ed in the dung, which might have furnished mucilage 
and sugar, as well as bitter extract, I examined the 
soluble matter very carefully for these substances. It 
did not yield an atom of sugar, and scarcely a sensible 
quantity of mucilage. 

Mr. Sinclair, in comparing the quantities of solu- 
ble matter afforded by the mixed leaves of the Lolium 
perenne, Dactylis glomerata, and Trifolium repens, 
and that obtained from the dung of cattle fed upon 
them, found their relative proportions as 50 to 1 3. 

It appears probable from these facts, that the bit- 
ter extract, though soluble in a large quantity of wa- 
ter, is very little nutritive; but probably it serves the 
purpose of preventing, to a certain extent, the fermen- 
tation of the other vegetable matters, or in modifying 
or assisting the function of digestion, and may thus 
be of considerable use in forming a constituent part 
of the food of cattle. A small quantity of bitter 
extract and saline matter is probably all that is needed, 
and beyond this quantity the soluble matters must be 
more nutritive in proportion as they contain more al- 



Lxxii APPENDIX. 

bumen, sugar, and mucilage, and less nutritive in pro- 
portion, as they contain other substances. 

In comparing the composition of the soluble pro- 
ducts afforded by different crops from the same grass, 
I found, in all the trials I made, the largest quantity 
of truly nutritive matter, in the crop cut when the seed 
was ripe, and least bitter extract and saline matter; 
most extract and saline matter in the autumnal crop; 
and most saccharine matter, in proportion to the other 
ingredients, in the crop cut at the time of flowering. 
I shall give one instance: 

100 parts of the soluble matter obtained from 
the Dactylis glomerata, cut in flower, afforded 
of sugar - - - - 18 parts 
of mucilage - - - 67 

of coloured extract, and saline matters, 
with some matter rendered insoluble by 
evaporation - - - 15 

100 parts of the soluble matter from the 
seed crop afforded 

Sugar 9 parts 

Mucilage - - - - 85 

Extract, insoluble, and saline matter 6 
100 parts of soluble matter from the after-math 
crop give 

of sugar - - - - 11 parts 

of mucilage _ . . 59 

of extract, insoluble, and saline matters 30 
The greater proportion of leaves in the spring, 
and particularly in the late autumnal crop, accounts 
for the difference in the quantity of extract; and the 



APPENDIX. Lxxiii 

inferiority of the comparative quantity of sugar in the 
summer crop, probably depends upon the agency of 
light, which tends always in plants to convert sacchar- 
ine matter into mucilage or starch. 

Amongst the soluble matters afforded by the 
different grasses, that of the Elymus arenarius was re- 
markable for the quantity of saccharine matter it con- 
tained, amounting to more than one third of its weight. 
The soluble matters from the different species of Fes* 
tuca, in general afford more bitter extractive matter 
than those from the different species of Poa. The 
nutritive matter from the seed crop of the Poa com- 
pressa wom almost pure mucilage. The soluble mat- 
ter of the seed crop of Phleum pratense, or meadow 
cat's-tail, afforded more sugar than any of the Poa or 
Festuca species. 

The soluble parts of the seed crop of the Holcus 
mollis and Holcus lanatus contained no bitter extract, 
and consisted entirely of mucilage and sugar. Those 
of the Holcus odoratus afforded bitter extract, and a 
peculiar substance having an acrid taste, more soluble 
in alcohol than in water. All the soluble extracts of 
those grasses that are most liked by cattle, have either 
a saline or subacid taste j that of the Holcus lanatus, 
is similar in taste to gum arable. Probably the Holcus 
lanatus which is so common a grass in meadows, might 
be made palatable to cattle by being sprinkled over 
with salt. 

I have found no differences in the nutritive pro- 
duce of the crops of the different grasses cut at the same 
season, which would render it possible to establish a 

K 



Lxxiv APPENDIX. 

scale of their nutritive powers; but probably the soluble 
matters of the after-math crop are always from one sixth 
to one third less nutritive than those from the flower 
or seed crop. In the after-math the extractive and 
saline matters are certainly usually in excess; but the 
after-math hay mixed with summer hay, particularly 
that in which the fox-tail and soft grasses are abun- 
dant, would procure an excellent food. 

Of the clovers, the soluble matter from the 
Dutch clover contains most mucilage, and most matter 
analogous to albumen: all the clovers contain more bit- 
ter extract and saline matter than the common proper 
grasses. When pure clover is to be mixed as fodder, 
it should be with sumujcr hay, rather thau after-math 
hay. 



INDEX. 



Acids, account of those found 
in vegetables, 96. 

Age of trees, by what limited, 
225. 

Alcohol, theory of its forma- 
tion, 19. 

Alburnum, uses of, 54, 225. 

Alkalies, method of ascertain- 
ing their presence in plants, 
99. 

effects produced by, in 

vegetation, 17 

Animal substances, their com- 
position, &c. 245 

— ——decomposition of, 244. 

Atmosphere, nature and con- 
stitution of, 183. 

Animal matter, mode of ascer- 
taining its existence in soils, 
148. 

Bark, its office and uses, 51, 

211. 
Barks, their relative value for 

tanning skin, 8 1 . 
Blight in corn, its cause, 236. 
Bread, its manufacture theory 

of its production, 123 
Burning, its use in improving 

soils, 3'J9. 

Canker in trees, probable mode 
of curing, 234. 

Carbonic acid, a part of the at- 
mosphere, 186, 

——necessary to vegetation, 
197. 



Cements, on those obtained 

from limestone, 290 
Chemistry, its application to 

agriculture, 5 

-importance in ag- 



ricultural pu suits, 2.3. 
Combustibles, simple, referred 

to, 40. 
Combustion, supporters of, 

mentioned 39. 
Courses of crops, particular 

ones recommen ed, 319. 
Corn, its tillering, theory of 

this operation, 207. 

Diseases of Plants, their causes 
discussed, 233. 

Earths, on those found in 
plants, 101. 

Electricity, its influence on ve- 
getation. 37. 

Elements chemical, of bodies, 
40. 

laws of their com- 



binations. 46. 
Excrements, use of as ma- 
nures, 261. 

Fairy rings, their causes, 319. 
Fallowing, theory of, 21, 315. 
Fermentation, phaenomena of, 

118. 
Fly-turnip, plan for destroying 

or preventing, 195. 
Flowers, their parts and officCj 

61, 



INDEX. 



Geology, referred to as teacK-' 
inj^ the nature of rocks, 170. 

Grafting, general views on this 
proccsa, 226 

Grasses, on those fit for pas- 
ture, 322. 

Gravitation, its effects on 
plants, 29. 

Green crops recommended, 
317. 

Gypsum, its use as a manure, 
293. 

Heat, its effects on vegetables, 

34, 158. 
jausbandry drill, its advan- 

tagesj 317. 

Ice, its anti-putrescent pow- 
ers, 248. 

Irrigation, theorjf of its effects, 
■ 313. 

Irritability, vegetable, its exis- 
tence doubted 216. 

Land, causes of its fertility, 

179. 

•■ barrenness 180. 

Leaves, their functions, 58. 
Light, its effect on vegetation, 

197. 
Limestone, its nature and uses, 

19, 281. 

-action in the soil, 19 



293. 



— mode of burning, 

— magnesian, its peculiar 

properties, 21, 287. 
Lime, mode of ascertaining 

the quantity in limestones 

and soils, 147. 
salts of, on the mode of 

detecting them in soils, 152, 

Manures on their applications, 
239 

" how taken into the ve- 
getable system, 240. 



Manur/^s, fermentation of, 6, 
; 269. 

' in what state to be 

used, r69. 

animal, 261. 

mineral, 285. 

vee;ctable, 249. 



— saline, 260, 279. 



Malting, theory of the process 

of, 192. 
Matter, powers of discussed, 

28. 
Metals, account of, 42. 
Metallic oxides, those found 

in plants. 104. 
Mildew, cause of, 236. 
Meat, method of preserving it, 

248. 

Oils, fi^ed, their nature and 
production, 92. 

Oxygene, its presence in the 
atmosphere, and uses, 188, 

necessary to germina- 
tion, 179,206. 

Paring and burning, theory of 
their operation, 309. 

Pasture, where advantageous, 
322. 

Plants, organization of,50il23. 

Plants, parasitical, described as 
the cause of disease in corn, 
234. 

Peat mosses, on their forma- 
tion, 169. 

on their improve- 



ment. 181. 

Putrefaction, methods of pre- 
venting, 248. 

Pith, nature of, 56. 

Plants, parts of, 50. 

Quicklime, injurious to soils, 
283. 

Rocks, their number and ar- 
rangement, 171. 



INDEX. 



Rocks, those from which soils 
are derived, or on which 
they rest, 175. 

Sap, cause of its ascent discus- 
sed, 211. 

course of 8, 209. 

its composition discus- 
sed, 131. 

Salts their uses as manure, 
261,279. 

—— — on such as are found in 
vegetables, 102. 

■— — on those found in soils, 
acrount of, 139. 

Seeds, on those produced by 
crossing, 229. 

germination of, 189. 

their nature and uses, 63. 

Simple substances described, 
40. 

Soils, properties of, 157, 142. 

composition of 136, 154. 

method of analysing, 140. 

formation of. ;66. 

their constituent parts, 

136. 

improvement of, 181. 

their classification, 178. 

Subsoils, vai'ieties of, and their 
effects, 166. 

Soot, properties of as a ma- 
nure, 274. 

Sugar, mode of refining, 71. 

Tanning principle, its applica- 
tion to tanning, 79, 

- ■■■« quantity in differ- 
ent barks, 80. 

artificial, 83. 



Temperatui'e of soils discus- 
sed, 158. 

Trees, habits of, discussed, 
233. 

' cause of their decay, 



Trees, age of, 226. 

Urine, its use as a manure, 
261. 

Vegetables, their chemical 
composition, 6f . 

improvement of, by cul- 



tivation, 228. 
renovation of the at- 



mosphere, 203. 

the causes of their 



growth discussed, 220. 

Vegetable matter, mode of as- 
certaining its quantity in 
soils, i48. 

its analysis, 107. 

decomposition of, 

described, 244. 

principles, their ar- 



rangement in plants, 123. 

Vegetable life, phaenomena of, 
discussed, 219. 

matter, decomposition 

of, 242. 

Vegetation, influenced by gra- 
vitation, 29. 

influence of light in, 



208. 



502. 



progress of, 195, 
its effect on a soil, 



11! 



Veins or mines, their situa- 
tions, 174. 

Water, absorption of by soils, 
161. 

its state in the atmos- 
phere, 186 

Wheat, transplantation of, 208. 

— crossing of, 228. 

Wines, theory of their forma- 
tion, 119. 

quantity of spirits they 

contain, 121. 



INDEX TO THE APPENDIX. 



Jgrostia canina, brown bent, 
lix. 



— : canina var, mutica, 

awnless brown bent, Ix. 

fascicularis, tufted-lea- 



ved bent, Ixi. 
— — / batUf 



lobed bent 



grass, Ixii 
mexicanuy 



mexican 



bent 



bent grass, Ixiii. 
iiiveuy snowy 

grass, Ixvi. 
fialustris, March bent 

grass, Ivii. 

refiens, creeping root- 



ed bent, Ixiii. 

stricta, upright bent 



grassj Ix. 

-* stolonifera florin creep- 



ing bent, iviii 
stolonifera var. an^us- 

tifolia^ creeping bent narrow 

leaves, lix. 
vulgaris^ fine bent 



grass, Ivi 
Jira aquatica^ water hair grass, 

xlvii. 
cxsfiitosa^ turfy hair grass 

xlviii. 
Jiexuosa, waved moun- 
tain hair grass, XXXV. 
Alopecurus agrcstis.^ slender 

fox-tail grass, Ixiv. 
alpinua, alpine fox 

tail grass, x, 
' pratenszs, meadow 

fox-tail grass, viii. 
Anthoxanthu7n doratum^ sweet 

scented vernal grass, v. 
Arundo colorata, striped-leaved 

reed grass, xli. 
Avena elatioVf tall oat grass, 

XXV. 



'■ — fiavescensf yellow oat 

grass, xlix. 
pratensisy meadow oat 

grass, xxxii. 

fiubescens) downy oat 

grass, X. 

Briza media, quaking grass, 

XX. 

Bromui asfier, Ixiv. 

cristatus, xlvii. 

diandruKy xxiii. 

erectus, upright peren- 
nial bronie grass, xxvii. 

inermis, awnless brome 



grass, Iv 

- lit/oreics, sea side 



brome grass, xxxvii. 

multiflorusy many 



flowering brome grass, xxxii. 
— tectorum, nodding pan - 



nicled brome grass, xxii. 

sterilts, barren brome 

grass, 1. 

Bunias orientalise xlii. 

Cynosurus caruleus, blue moor 

grass, vii. 
Cynosurus cristatus, crested 

dog's-tail grass, xxxi. 

erucaformisy linear 

spiked dog's-tail grass, lii. 

Dactylis cynosuroiiesy Ameri- 
can cock's foot grass, Ixv. 
glomerata, round-headr 



ed cock's foot grass, xxi. 

Etymus arenariusy upright sea 
iyme grass Iv. 

- geniculatusf pendulous 



sea Jyme grass, l\\ 



INDEX. 



Elymua sibericusi Siberian 
lyme grass, xlviii. 

Festuca caiamaria, reed-like 

fescue grass, xxxv. 
- cambrica, xxd. 
duriusculuy hard fescue 

grass, xxvi. / 

-— c?M77ze;orM2>^ pubescent 

fescue grass, XI. 
■ ■ — ilatioi\ivL\\ fescue grass 



XXXVIU. 

Jluitans^ floating fes- 
cue grass, xxxix. 
glabra, smooth fescue 



grass, XVI. 

glaucOf glaucares fes- 
cue grass, XV. 

J.' or dif ormis .h&r\ey like 



fescue grass, xiii. 
— — loUaceat spiked fescue 



grass, xxxiii. 
tjiyurusf wall fescue 

grass, xxxiv. 
■ ovina, sheeps' fescue 



grass, XIX. 

/lenna a, spiked fescue 



grass, Ixi. 
firatensis, meadow fes- 



cue grass, xxvm. 
rubra, purple fescue 



grass, xviu. 

Hedysarum onobrychisy sain- 
foin, xlv. 

Hordeum biilbosum, bulbous 
barley grass, xxxv. 

marinum, wall barley 

grass, xlviii 

firatense, meadow bai^ 



ley grass, xlvi. 
Holcua lanatus, meadow soft 

grass, xl- 
mollia, creeping soft 

glass, 1 

odoratusy sweet-scent- 



Lolium fierenne, perennial rye 
grass, xxix. 

Medicago saiiva, lucerne, xlv. 

Melica cxulea, purple malic 
^rass, Ixv. 

Milium effusum, common mil- 
let grass, xxviii. 

Mirdu7n stricta, upright mat 
grass, xxxix. 

Panicum dactylon, creeping 
panic grass, Iviii 

sangui72ale, blood-co- 
loured panic grass, Ixii. 

viride, green panic 

grass, Ixi. 

Phalaris cunaniensis, common 
canary grass, Ixv. 

PlUeum nodosum, bulbous- 
stalked cat's-tail grass. Hi. 
firatense, meadow 



cat's-tail grass, liii, 
T/ar, minor, meadow 



cd soft grass, vi. 



cat's-tail grass, var. smaller, 

liv. 
Poa alpina, alpine meadow 

grass- X. 
— — — — angus ifolia, narrow» 

leaved meadow grass xxiii..; 

aquatica, reed meadow 

grass xlvJi. 

cxrulea, -v. p. pretense. 



short bluish meadow grass, 
xiii. 

compressa, flat-stalked 



meadow grass, xlvi. 

cristata, crested mea- 



dow grass, xxxiv. 
elatior, tall meadow 

grass, xxvi. 
fer tills, fertile meadow 

grass, xli. 
var, 6, fertile 

meadow grass, var. I. li. 
maritim; sea meadow 



grass, XXX, 



INDEX. 



^na firatetisis, smooth 

stalked meadow grass, xii. 
■ trivialis, roughish mea- 



dow grass, xiv. 
Potirium savguisorba, burnet, 
xxxvii. 

Stifia fiennatu, long armed fea- 
ther grass, Ixiii. 



Trifolium viacrorhizum^ long 
rooted clover, xxx\ iii. 

firatense, broad lea- 
ved cultivated clover, xlii. 

— refiens, white clover, 

Ixi'u. 

Triticum refiens, creeping root- 
ed wheat grass, Ixiv. 

5/*. wheat grass, 



xxxix. 



FINIS. 



T?w-A-, 



LIBRARY OF CONGRESS 



DDDEt)71fiE7E 



